Algebra 1A. Unit 04. Chapter 3 sections 1-9 Chapter 4 section 7-8 GUIDED NOTES NAME. Teacher. Period

Transcription

1 Algebra 1A Unit 04 Chapter 3 sections 1-9 Chapter 4 section 7-8 GUIDED NOTES NAME Teacher Period

2 Section 3-1: Writing Equations Notes Date: Writing Equations: Some verbal expressions that suggest the equals sign: Example #1: Translate each sentence into an equation. a.) Nine times y subtracted from 95 equals 37. b.) A number b divided by three is equal to six less than c. c.) Five times the number a is equal to three times the sum of b and c. Four-Step Problem-Solving Plan: 1.) 2.) 3.) 4.) Example #2: You know that 2,000,000 gallons of ice cream are produced in the United States each day. You want to know how many days it will take to produce 40,000,000 gallons of ice cream. Use the Four-Step Plan. 1 1

3 Example #3: A popular jellybean manufacturer produces 1,250,000 jellybeans per hour. How many hours does it take them to produce 10,000,000 jellybeans? Use the Four-Step Plan. Example #4: Translate the sentence into a formula. The perimeter of a square equals four times the length of the side. Example #5: Translate the sentence into a formula. The perimeter of a rectangle equals two times the length plus two times the width. Writing Verbal Sentences: Example #4: Translate each equation into a verbal sentence. a.) 12 2x = 5 b.) a + 3b = 6 2 c c.) 3 m + 5 = 14 d.) w + v = 2 y 2 2

4 Date: Section 3-2: Solving Equations by Using Addition and Subtraction Notes Part 1 Solve Using Addition: ADDITION PROPERTY OF EQUALITY: Example #1: Solve the following equations by using the Addition Property of Equality. a.) m 48 = 29 b.) h 12 = 27 c.) 14 + s = 23 d.) k 2.04 = Solve Using Subtraction: SUBTRACTION PROPERTY OF EQUALITY: Example #2: Solve the following equations by using the Subtraction Property of Equality. a.) d + 97 = 142 b.) k + 63 = 92 c.) 47 + m = 86 d.) 4 y + =

5 e.) g ( 4) = 17 f.) 18 ( f ) = 91 Solve by Adding or Subtracting: Example #3: Solve the following. a.) c +102 = 36 b.) 17 + t = 34 c.) 2 1 y = d.) = a e.) 1 2 b + = f.) k ( 8) =

6 Date: Section 3-2: Solving Equations by Using Addition and Subtraction Notes Part 2 Write an equation for the following problems. Then solve the equations and check your solutions. 1.) A number increased by 5 is equal to 42. Find the number. 2.) Fourteen more than a number is equal to twenty seven. Find the number. 3.) Twenty one subtracted from a number is 8. Find the number. 4.) A number increased by 37 is 91. Find the number. 5.) The Washington Monument in Washington, D.C., was built in two phases. During the first phase, from , the monument was built to a height of 152 feet. From 1854 until 1878, no work was done. Then from 1878 to 1888, the additional construction resulted in its final height of 555 feet. How much of the monument was added during the second construction phase? Write an equation to solve the problem. 1 5

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8 Date: Section 3-3: Solving Equations by Using Multiplication and Division Notes Solve Using Multiplication: MULTIPLICATION PROPERTY OF EQUALITY: Example #1: Solve the following equations by using the Multiplication Property of Equality. x a.) 7 8 = b.) z 3 15 = 5 c.) 9 = k d.) g = Solve Using Division: DIVISION PROPERTY OF EQUALITY: Example #2: Solve the following equations by using the Division Property of Equality. a.) 3 y = 21 b.) 2g =

9 c.) 7 t = 77 d.) 2 3 f = 4 3 Solve Using Multiplication or Division: Example #3: Solve the following. a.) s 3 11 = 4 b.) k = c.) 75 = 15b d.) 11 w = 143 e.) 8 x = 96 Write and Solve an Equation: Example #4: Write an equation for the problems below. Then solve the equations. a.) Negative fourteen times a number equals 224. b.) One sixth times the weight on Earth equals the weight on the moon. 2 8

10 Section 3-4: Solving Multi-Step Equations Notes Date: Multi-Step Equations: Example #1: Solve each equation. Then check your solution. a.) 7 m 17 = 60 b.) 5 q 13 = 37 t c.) + 21 = 14 8 s d.) 9 = p 15 e.) = 6 9 r + 8 f.) =

11 Example #2: Write an equation and solve each problem. a.) Twelve is eight plus two times a number. b.) Eight more than five times a number is negative 42. c.) Find three consecutive integers whose sum is 96. Example #3: Solve each equation. Then check your solution. a.) 5 x + 2 = 27 b.) 6 x + 9 = 27 c.) 5 x + 16 = 51 7 d.) 14 n 8 = 34 e.) 0.6x 1.5 = 1. 8 f.) p 4 = 10 8 g.) = d g h.) + 3 = i.) 7x ( 1) 4 =

12 Date: Section 3-5: Solving Equations with the Variable on Each Side Notes Variables on Each Side: Example #1: Solve each equation. Then check your solution. a.) x = 8x 1 b.) 8 + 5p = 7 p c.) 4 (2r 8) = (49r + 70) d.) ( y ) = 6(2y 7) 7 3 e.) 2m + 5 = 5( m 7) 3m f.) 8(5c 2) = 10(32 + 4c) 1 g.) 3( r + 1) 5 = 3r 2 h.) 4 ( t + 20) = (20t + 400)

13 Example #2: Write and equation and solve. The sum of one half of a number and 6 equals one third of the number. What is the number? Example #3: When exercising, a person s pulse rate should not exceed a certain limit, which depends on his or her age. This maximum rate is represented by the expression 0.8(220 a), where a is age in years. Find the age of a person whose maximum pulse is 152. Show all work! 2 12

14 Ratios and Proportions: Section 3-6: Ratios and Proportions Notes Part 1 Ratio a comparison of numbers by The ratio of x to y can be expressed in the following ways: 1.) 2.) 3.) Date: What is the ratio of girls to boys in this classroom? What is the ratio of teachers to students in this classroom? What is the ratio of boys to all students in this classroom? *** Remember Simplify your ratios!!! Proportion an equation stating that two are Example #1: Determine whether the following pairs of ratios are proportional. a.) 3 2 and b.) and c.) and

15 Example #2: Use cross products to determine whether each pair of ratios form a proportion. a.) 0.4, b.) 6, Means and Extremes If a c =, then ad = bc b d Example #3: Solve each proportion. a.) n = 16 b.) n = c.) = 4 x

16 Section 3-6: Ratios and Proportions Notes Part 2 Date: Create a proportion for each situation and solve. Show all of your work! 1.) Tom earns $152 in 4 days. At that rate, how many days will it take him to earn $532? 2.) Ashely drove 248 miles in 4 hours. At that rate, how long will it take her drive an additional 93 miles? 3.) A blueprint for a house states that 2.5 inches equals 10 feet. If the length of a wall is 12 feet, how long is the wall in the blueprint? 4.) A research study shows that three out of every twenty pet owners got their pet from a breeder. Of the 122 animals cared for by a veterinarian, how many would you expect to have been bought from a breeder? 1 15

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18 Section 3-7: Percent of Change Notes Date: Percent of Change: Percent of Change when an or is expressed as a percent Example #1: State whether each percent of change is a percent of increase or a percent of decrease. Then find each percent of change. a.) original: 25 b.) original : 20 c.) original: 32 new: 28 new: 4 new: 40 Example #2: Find amount after sales tax. a.) A meal for two at a restaurant costs $ If the sales tax is 7%, what is the total price of the meal? b.) A concert ticket costs $45. If the sales tax is 6.25%, what is the total price of the ticket? 1 17

19 Example #3: Find amount after discount. a.) A dog toy is on sale for 20% off the original price. If the original price of the toy is $3.80, what is the discounted price? b.) A sweater is on sale for 35% off the original price. If the original price of the sweater is $38, what is the discounted price? Example #4: Find amount after discount and sales tax. A shirt costs $45. It is discounted for 20%, and has a sales tax of 5.5%. What is the final sale price of the shirt? Example #5: The National Football League s (NFL) fields are 120 yards long. The Canadian Football League s (CFL) fields are 25% longer. What is the length of a CFL field? 2 18

20 Section 3-8: Solving Equations and Formulas Notes Date: Solve For Variables: Some equations contain more than one variable. At times, you will need to solve these equations for one of the variables. Example #1: Solve the following equations for the variable specified. a.) 3 x 4y = 7, for y b.) 2 m t = sm + 5, for m y + a c.) p = a( b + c), for a d.) = c, for y 3 Use Formulas: Many real-world problems require the use of formulas. Sometimes solving a formula for a specific variable will help you solve the problem. Example #2: The formula for the circumference of a circle is C = 2π r, where C represents circumference and r represents radius. a.) Solve the formula for r. b.) Find the radius if the circumference is 9.5 inches. 1 19

21 Algebra 1 Name Cost, Income, and Value Notes Date Pd Steps to solving Cost, Income, Value Problems: Example 1: Tickets for a concert cost $8 for adults and $4 for students. A total of 920 tickets worth $5760 were sold. How many adult tickets were sold? Number X Price = Cost Adult a Student Example 2: Tickets for the senior class play cost $6 for adults and $3 for students. A total of 846 tickets worth $3846 were sold. How many student tickets were sold? Number X Price = Cost Adult Student s 20

22 Example 3: An apple sells for 25 cents and a peach cells for 15 cents. A total of 10 pieces of fruit were sold for a total cost of $2.10. How many apples were sold? Number X Price per Fruit = Cost Apple a Peach Example 4: Coria and Kip went to the record store during its sale. Together they spent $ If each record cost $3.50 and Kip bought one more than Coria, how many records did each buy? Number X Price = Cost Coria r Kip 21

23 Algebra 1 Name Mixture Notes Date Pd Steps to solving Mixture Problems: Example 1: A health food store sells a mixture of raisins and roasted nuts. Raisins sell for $4 / kg and nuts sell for $6 / kg. How many kg of each should be mixed to make 40 kg of this snack worth $4.75 / kg? Number of kg X Price per kg = Cost Raisins c Nuts Mixture Example 2: A grocer makes a natural breakfast cereal by missing oat cereal costing $2 / kg with dried fruits costing $9 / kg. How many kg of each are needed to make 60 kg of cereal costing $3.75 / kg? Number of kg X Price per kg = Cost Cereal c Fruit Mixture 22

24 Example 3: A chemist has 60 ml of a solution that is 70% acid. How much water should be added to make a solution that is 40% acid? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution Example 4: An auto mechanic has 300 ml of battery acid solution that is 60% acid. He must add water to this solution to dilute it so that it is only 45% acid. How much water should he add? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution 23

25 Algebra 1 Name Rate Time Distance Notes Date Pd Steps to solving Rate Time Distance Problems: Example 1: Two jets leave St. Louis at 8 am one flying east at a speed 40 km / h greater than the other, which is traveling west. At 10 am the planes are 2480 km apart. Find their speeds. Rate X Time = Distance East West r Example 2: Bicyclists Brent and Jane started at noon from points 60 km apart and rode toward each other, meeting at 1:30 pm. Brent s speed was 4 km / h greater than Jane s speed. Find their speeds. Rate X Time = Distance Brent Jane r 24

26 Example 3: A helicopter leaves Central Airport and flies north at 180 mph. Twenty minutes later a plane leaves the airport and follows the helicopter at 330 mph. How long does it take the plane to overtake the helicopter? Rate X Time = Distance Helicopter Plane p Example 4: A ski lift carried Marie up a slope at the rate of 6 km / h, and she skied back down parallel to the lift at 34 km / h. The round trip took 30 minutes. How far did she ski and for how long? Rate X Time = Distance Up Down S 25

27 3-1 NAME DATE PERIOD Study Guide and Intervention Writing Equations Write Equations Writing equations is one strategy for solving problems. You can use a variable to represent an unspecified number or measure referred to in a problem. Then you can write a verbal expression as an algebraic expression. Example 1 Example 2 Translate each sentence into an equation or a formula. a. Ten times a number x is equal to 2.8 times the difference y minus z. 10 x 2.8 ( y z) The equation is 10x 2.8( y z). b. A number m minus 8 is the same as a number n divided by 2. m 8 n 2 n The equation is m 8. 2 c. The area of a rectangle equals the length times the width. Translate this sentence into a formula. Let A area, length, and w width. Formula: Area equals length times width. A w The formula for the area of a rectangle is A w. Exercises Use the Four-Step Problem-Solving Plan. The population of the United States in 2001 was about 284,000,000, and the land area of the United States is about 3,500,000 square miles. Find the average number of people per square mile in the United States. Source: Step 1 Explore You know that there are 284,000,000 people. You want to know the number of people per square mile. Step 2 Plan Write an equation to represent the situation. Let p represent the number of people per square mile. 3,500,000 p 284,000,000 Step 3 Solve 3,500,000 p 284,000,000. 3,500,000p 284,000,000 Divide each side by p ,500,000. There about 81 people per square mile. Step 4 Examine If there are 81 people per square mile and there are 3,500,000 square miles, 81 3,500, ,500,000, or about 284,000,000 people. The answer makes sense. Lesson 3-1 Translate each sentence into an equation or formula. 1. Three times a number t minus twelve equals forty. 2. One-half of the difference of a and b is Three times the sum of d and 4 is The area A of a circle is the product of and the radius r squared. WEIGHT LOSS For Exercises 5 6, use the following information. Lou wants to lose weight to audition for a part in a play. He weighs 160 pounds now. He wants to weigh 150 pounds. 5. If p represents the number of pounds he wants to lose, write an equation to represent this situation. 6. How many pounds does he need to lose to reach his goal? Glencoe/McGraw-Hill 137 Glencoe Algebra 1 26

28 3-1 NAME DATE PERIOD Skills Practice Writing Equations Translate each sentence into an equation. 1. Two added to three times a number m is the same as Twice a increased by the cube of a equals b. 3. Seven less than the sum of p and q is as much as The sum of x and its square is equal to y times z. 5. Four times the sum of f and g is identical to six times g. Translate each sentence into a formula. 6. The perimeter P of a square equals four times the length of a side s. 7. The area A of a square is the length of a side s squared. Lesson The perimeter P of a triangle is equal to the sum of the lengths of sides a, b, and c. 9. The area A of a circle is pi times the radius r squared. 10. The volume V of a rectangular prism equals the product of the length, the width w, and the height h. Translate each equation into a verbal sentence. 11. g 10 3g 12. 2p 4q (a b) 9a x 4 2x ( f y) f s 2 n 2 2b 2 Write a problem based on the given information. 17. c cost per pound of plain coffee beans 18. p cost of dinner c 3 cost per pound of flavored coffee beans 0.15p cost of a 15% tip 2c (c 3) 21 p 0.15p 23 Glencoe/McGraw-Hill 139 Glencoe Algebra 1 27

29 3-2 NAME DATE PERIOD Study Guide and Intervention (continued) Solving Equations by Using Addition and Subtraction Solve Using Subtraction If the same number is subtracted from each side of an equation, the resulting equation is equivalent to the original one. In general if the original equation involves addition, this property will help you solve the equation. Subtraction Property of Equality For any numbers a, b, and c, if a b, then a c b c. Example Solve 22 p p 12 Original equation 22 p Subtract 22 from each side. p 34 Simplify. The solution is 34. Exercises Solve each equation. Then check your solution. 1. x z b s ( 9) ( 0.2) 6. x h k j b m ( 8) w 2 8 Write an equation for each problem. Then solve the equation and check the solution. 13. Twelve added to a number equals 18. Find the number. 14. What number increased by 20 equals 10? 15. The sum of a number and fifty equals eighty. Find the number. 16. What number plus one-half is equal to four? 17. The sum of a number and 3 is equal to 15. What is the number? Glencoe/McGraw-Hill 144 Glencoe Algebra 1 28

30 3-2 NAME DATE PERIOD Skills Practice Solving Equations by Using Addition and Subtraction Solve each equation. Then check your solution. 1. y w p x b y s ( 28) 0 8. y ( 10) s ( 19) 10. j ( 17) d ( 10) 12. u ( 5) y 14. c ( 3) w ( 8) 16. x ( 74) 22 Lesson ( h) ( e) Write an equation for each problem. Then solve the equation and check your solution. 19. A number decreased by 14 is 46. Find the number. 20. Thirteen subtracted from a number is 5. Find the number. 21. The sum of a number and 67 is equal to 34. Find the number. 22. What number minus 28 equals 2? 23. A number plus 73 is equal to 27. What is the number? 24. A number plus 17 equals 1. Find the number. 25. What number less 5 is equal to 39? Glencoe/McGraw-Hill 145 Glencoe Algebra 1 29

31 3-3 NAME DATE PERIOD Study Guide and Intervention (continued) Solving Equations by Using Multiplication and Division Solve Using Division To solve equations with multiplication and division, you can also use the Division Property of Equality. If each side of an equation is divided by the same number, the resulting equation is true. a b Division Property of Equality For any numbers a, b, and c, with c 0, if a b, then. c c Example 1 Example 2 8n 64 8n n 8 Solve 8n 64. Original equation Divide each side by 8. Simplify. The solution is 8. 5n 60 5n n 12 Solve 5n 60. Original equation Divide each side by 5. Simplify. The solution is 12. Exercises Solve each equation. Then check your solution. 1. 3h m t r k m h p j m 11. 6m p 75 Write an equation for each problem. Then solve the equation. 13. Four times a number equals 64. Find the number. 14. What number multiplied by 4 equals 16? 15. A number times eight equals 36. Find the number. Glencoe/McGraw-Hill 150 Glencoe Algebra 1 30

32 3-3 NAME DATE PERIOD Skills Practice Solving Equations by Using Multiplication and Division Solve each equation. Then check your solution z t e v 5. 6d a c a d d t n z 14. q a p b m 4 Write an equation for each problem. Then solve the equation. 19. The opposite of a number is 9. What is the number? Lesson Fourteen times a number is 42. Find the number. 21. Eight times a number equals 128. What is the number? 22. Negative twelve times a number equals 132. Find the number. 23. Negative eighteen times a number is 54. What is the number? 24. One sixth of a number is 17. Find the number. 25. Negative three fifths of a number is 15. What is the number? Glencoe/McGraw-Hill 151 Glencoe Algebra 1 31

33 3-4 Solve Multi-Step Equations To solve equations with more than one operation, often called multi-step equations, undo operations by working backward. Reverse the usual order of operations as you work. Example NAME DATE PERIOD 5x x x 20 5x x 4 Study Guide and Intervention (continued) Solving Multi-Step Equations Solve 5x Original equation. Subtract 3 from each side. Simplify. Divide each side by 5. Simplify. Exercises Solve each equation. Then check your solution. 1. 5x x x n x p d 12 3n g b x y x ( 1) k y Write an equation and solve each problem. 16. Find three consecutive integers whose sum is Find two consecutive odd integers whose sum is Find three consecutive integers whose sum is 93. Glencoe/McGraw-Hill 156 Glencoe Algebra 1 32

34 3-4 NAME DATE PERIOD Skills Practice Solving Multi-Step Equations Solve each problem by working backward. 1. A number is divided by 2, and then the quotient is added to 8. The result is 33. Find the number. 2. Two is subtracted from a number, and then the difference is divided by 3. The result is 30. Find the number. 3. A number is multiplied by 2, and then the product is added to 9. The result is 49. What is the number? 4. ALLOWANCE After Ricardo received his allowance for the week, he went to the mall with some friends. He spent half of his allowance on a new paperback book. Then he bought himself a snack for $1.25. When he arrived home, he had $5.00 left. How much was his allowance? Solve each equation. Then check your solution. 5. 5x a y c w v 42 n x h d a w q g z c 5 b m Write an equation and solve each problem. 23. Twice a number plus four equals 6. What is the number? Lesson Sixteen is seven plus three times a number. Find the number. 25. Find two consecutive integers whose sum is Find three consecutive integers whose sum is 36. Glencoe/McGraw-Hill 157 Glencoe Algebra 1 33

35 3-6 NAME DATE PERIOD Study Guide and Intervention (continued) Ratios and Proportions Solve Proportions If a proportion involves a variable, you can use cross products to solve x 10 the proportion. In the proportion, x and 13 are called extremes and 5 and 10 are 5 13 called means. In a proportion, the product of the extremes is equal to the product of the means. a c Means-Extremes Property of Proportions For any numbers a, b, c, and d, if, then ad bc. b d Example 11 The solution is x 10 Solve x Original proportion 13(x) 5(10) Cross products 13x 50 Simplify. 13x Divide each side by x 3 13 Simplify. Exercises Solve each proportion x 8 t 3 2 x x x x p y 1 54 d y y b 2 12 x x 4 8 a w k k 6 9 Use a proportion to solve each problem. 16. MODELS To make a model of the Guadeloupe River bed, Hermie used 1 inch of clay for 5 miles of the river s actual length. His model river was 50 inches long. How long is the Guadeloupe River? 17. EDUCATION Josh finished 24 math problems in one hour. At that rate, how many hours will it take him to complete 72 problems? Glencoe/McGraw-Hill 168 Glencoe Algebra 1 34

36 3-6 NAME DATE PERIOD Skills Practice Ratios and Proportions Use cross products to determine whether each pair of ratios forms a proportion. Write yes or no , 2., , 4., Lesson , 6., , 8., Solve each proportion. If necessary, round to the nearest hundredth a 14 b g 10 a z 5 e y s f b n m c g 4 s x BOATING Hue s boat used 5 gallons of gasoline in 4 hours. At this rate, how many gallons of gasoline will the boat use in 10 hours? Glencoe/McGraw-Hill 169 Glencoe Algebra 1 35

37 3-7 Solve Problems Discounted prices and prices including tax are applications of percent of change. Discount is the amount by which the regular price of an item is reduced. Thus, the discounted price is an example of percent of decrease. Sales tax is amount that is added to the cost of an item, so the price including tax is an example of percent of increase. Example NAME DATE PERIOD Study Guide and Intervention (continued) Percent of Change A coat is on sale for 25% off the original price. If the original price of the coat is $75, what is the discounted price? The discount is 25% of the original price. 25% of $ % Use a calculator. Subtract $18.75 from the original price. $75 $18.75 $56.25 The discounted price of the coat is $ Exercises Find the final price of each item. When a discount and a sales tax are listed, compute the discount price before computing the tax. 1. Compact disc: $16 2. Two concert tickets: $28 3. Airline ticket: $ Discount: 15% Student discount: 28% Superair discount: 33% 4. Shirt: $ CD player: $ Celebrity calendar: $10.95 Sales tax: 4% Sales tax: 5.5% Sales tax: 7.5% 7. Class ring: $ Software: $ Video recorder: $ Group discount: 17% Discount: 21% Discount: 20% Sales tax: 5% Sales tax: 6% Sales tax: 5% 10. VIDEOS The original selling price of a new sports video was $ Due to the demand the price was increased to $ What was the percent of increase over the original price? 11. SCHOOL A high school paper increased its sales by 75% when it ran an issue featuring a contest to win a class party. Before the contest issue, 10% of the school s 800 students bought the paper. How many students bought the contest issue? 12. BASEBALL Baseball tickets cost $15 for general admission or $20 for box seats. The sales tax on each ticket is 8%, and the municipal tax on each ticket is an additional 10% of the base price. What is the final cost of each type of ticket? Glencoe/McGraw-Hill 174 Glencoe Algebra 1 36

38 3-7 NAME DATE PERIOD Skills Practice Percent of Change State whether each percent of change is a percent of increase or a percent of decrease. Then find each percent of change. Round to the nearest whole percent. 1. original: original: 50 new: 10 new: original: original: 25 new: 50 new: original: original: 90 new: 30 new: original: original: 60 new: 60 new: 45 Lesson 3-7 Find the total price of each item. 9. dress: $ binder: $14.50 tax: 5% tax: 7% 11. hardcover book: $ groceries: $47.52 tax: 6% tax: 3% 13. filler paper: $ shoes: $65.00 tax: 6.5% tax: 4% 15. basketball: $ concert tickets: $48.00 tax: 6% tax: 7.5% Find the discounted price of each item. 17. backpack: $ monitor: $ discount: 20% discount: 50% 19. CD: $ shirt: $25.50 discount: 20% discount: 40% 21. sleeping bag: $ coffee maker: $ discount: 25% discount: 45% Glencoe/McGraw-Hill 175 Glencoe Algebra 1 37

39 3-8 Use Formulas Many real-world problems require the use of formulas. Sometimes solving a formula for a specified variable will help solve the problem. Example The formula C d represents the circumference of a circle, or the distance around the circle, where d is the diameter. If an airplane could fly around Earth at the equator without stopping, it would have traveled about 24,900 miles. Find the diameter of Earth. C d Given formula C d Solve for d. 24,900 d 3.14 Use d 7930 Simplify. The diameter of Earth is about 7930 miles. Exercises NAME DATE PERIOD Study Guide and Intervention (continued) Solving Equations and Formulas 1. GEOMETRY The volume of a cylinder V is given by the formula V r 2 h, where r is the radius and h is the height. a. Solve the formula for h. b. Find the height of a cylinder with volume 2500 feet and radius 10 feet. 2. WATER PRESSURE The water pressure on a submerged object is given by P 64d, where P is the pressure in pounds per square foot, and d is the depth of the object in feet. a. Solve the formula for d. b. Find the depth of a submerged object if the pressure is 672 pounds per square foot. 3. GRAPHS The equation of a line containing the points (a, 0) and (0, b) is given by the x y formula 1. a b a. Solve the equation for y. b. Suppose the line contains the points (4, 0), and (0, 2). If x 3, find y. 4. GEOMETRY The surface area of a rectangular solid is given by the formula S 2 w 2 h 2wh, where length, w width, and h height. a. Solve the formula for h. b. The surface area of a rectangular solid with length 6 centimeters and width 3 centimeters is 72 square centimeters. Find the height. Glencoe/McGraw-Hill 180 Glencoe Algebra 1 38

40 3-8 NAME DATE PERIOD Skills Practice Solving Equations and Formulas Solve each equation or formula for the variable specified. 1. 7t x, for t 2. e wp, for p 3. q r r, for r 4. 4m n m, for m 5. 7a b 15a, for a 6. 5c d 2c, for c 7. x 2y 1, for y 8. m 3n 1, for n 9. 7f g 5, for f 10. ax c b, for x 11. rt 2n y, for t 12. bc 3g 2k, for c 13. kn 4f 9v, for n 14. 8c 6j 5p, for c Lesson 3-8 x c x c 15. d, for x 16. d, for c 2 2 p 9 b 4z 17. q, for p 18. a, for b 5 7 Write an equation and solve for the variable specified. 19. Five more than a number g is six less than twice a number h. Solve for g. 20. One fourth of a number q is three more than three times a number w. Solve for q. 21. Eight less than a number s is three more than four times a number t. Solve for s. Glencoe/McGraw-Hill 181 Glencoe Algebra 1 39

41 3-9 Uniform Motion Problems Motion problems are another application of weighted averages. Uniform motion problems are problems where an object moves at a certain speed, or rate. Use the formula d rt to solve these problems, where d is the distance, r is the rate, and t is the time. Example NAME DATE PERIOD Bill Gutierrez drove at a speed of 65 miles per hour on an expressway for 2 hours. He then drove for 1.5 hours at a speed of 45 miles per hour on a state highway. What was his average speed? M Study Guide and Intervention (continued) Weighted Averages Definition of weighted average Simplify. Bill drove at an average speed of about 56.4 miles per hour. Exercises 1. TRAVEL Mr. Anders and Ms. Rich each drove home from a business meeting. Mr. Anders traveled east at 100 kilometers per hour and Ms. Rich traveled west at 80 kilometers per hours. In how many hours were they 100 kilometers apart. 2. AIRPLANES An airplane flies 750 miles due west in 1 hours and 750 miles due south in 2 hours. What is the average speed of the airplane? 3. TRACK Sprinter A runs 100 meters in 15 seconds, while sprinter B starts 1.5 seconds later and runs 100 meters in 14 seconds. If each of them runs at a constant rate, who is further in 10 seconds after the start of the race? Explain TRAINS An express train travels 90 kilometers per hour from Smallville to Megatown. A local train takes 2.5 hours longer to travel the same distance at 50 kilometers per hour. How far apart are Smallville and Megatown? 5. CYCLING Two cyclists begin traveling in the same direction on the same bike path. One travels at 15 miles per hour, and the other travels at 12 miles per hour. When will the cyclists be 10 miles apart? 6. TRAINS Two trains leave Chicago, one traveling east at 30 miles per hour and one traveling west at 40 miles per hour. When will the trains be 210 miles apart? Glencoe/McGraw-Hill 186 Glencoe Algebra 1 40

42 3-9 NAME DATE PERIOD Skills Practice Weighted Averages SEASONING For Exercises 1 4, use the following information. A health food store sells seasoning blends in bulk. One blend contains 20% basil. Sheila wants to add pure basil to some 20% blend to make 16 ounces of her own 30% blend. Let b represent the amount of basil Sheila should add to the 20% blend. 1. Complete the table representing the problem. Ounces Amount of Basil 20% Basil Blend 100% Basil 30% Basil Blend 2. Write an equation to represent the problem. 3. How many ounces of basil should Sheila use to make the 30% blend? 4. How many ounces of the 20% blend should she use? HIKING For Exercises 5 7, use the following information. At 7:00 A.M., two groups of hikers begin 21 miles apart and head toward each other. The first group, hiking at an average rate of 1.5 miles per hour, carries tents, sleeping bags, and cooking equipment. The second group, hiking at an average rate of 2 miles per hour, carries food and water. Let t represent the hiking time. 5. Copy and complete the table representing the problem. First group of hikers r t d rt Lesson 3-9 Second group of hikers 6. Write an equation using t that describes the distances traveled. 7. How long will it be until the two groups of hikers meet? SALES For Exercises 8 and 9, use the following information. Sergio sells a mixture of Virginia peanuts and Spanish peanuts for $3.40 per pound. To make the mixture, he uses Virginia peanuts that cost $3.50 per pound and Spanish peanuts that cost $3.00 per pound. He mixes 10 pounds at a time. 8. How many pounds of Virginia peanuts does Sergio use? 9. How many pounds of Spanish peanuts does Sergio use? Glencoe/McGraw-Hill 187 Glencoe Algebra 1 41

43 Algebra 1 COST, INCOME, AND VALUE PROBLEMS Name Solve by completing the chart. Show all work. 1. Forty students bought caps at the baseball game. Plain caps cost $4 and deluxe ones cost $6 each. If the total bill was $236, how many students bought the deluxe cap? Number X Price = Cost Deluxe d Plain 2. Adult tickets for the game cost $6 each and student tickets cost 43 each. A total of 1040 tickets worth $5400 were sold. How many student tickets were sold? Number X Price = Cost Adult Student s 3. A collection of 60 dimes and nickels is worth $4.80. How many dimes are there? Number X Value of Coin = Total Value Dimes d Nickels 4. A collection of 54 dimes and nickels is worth $3.80. How many nickels are there? Number X Value of Coin = Total Value Dimes Nickels n 42

44 5. Henry paid $.80 for each bag of peanuts. He sold all but 20 of them for $1.50 and made a profit of $54. How many bags did he buy? (Hint: Profit = selling price buying price.) Number X Price = Cost Bought b Sold 6. Paula paid $4 for each stadium cushion. She sold all but 12 of them for $8 each and made a profit of $400. How many cushions did she buy? (Hint: Profit = selling price buying price.) Number X Price = Cost Bought b Sold 7. I have three times as many dimes as quarters. If the coins are worth $6.60, how many quarters are there? Number X Value of Coin = Total Value Dimes Quarters q 8. I have 12 more nickels than quarters. If the coins are worth $5.40, how many nickels are there? Number X Value of Coin = Total Value Quarters Nickels n 43

45 Algebra 1 MIXTURE PROBLEMS Name Solve by completing the chart. Show all work. 1. The owner of a specialty food store wants to mix cashews selling at $8.00 / kg and pecans selling at $6.00 / kg. How many kilograms of each should be mixed to get 12 kg of nuts worth $7.50 / kg? Number of kg X Price per kg = Cost Cashews c Pecans Mixture 2. A grocer mixed 12 pounds of egg noodles costing $.80 / lb with 3 lbs of spinach noodles costing $1.20 / lb. What will the cost of the mixture be? Number of kg X Price per kg = Cost Egg Noodles Spinach Noodles Mixture c 3. A special tea blend is made from two varieties of herbal tea, one that costs $4.00 / kg and another that costs $2.00 / kg. How many kilograms of each type are needed to make 20 kg of blend worth $2.50 / kg? Number of kg X Price per kg = Cost Tea 1 t Tea 2 Mixture 44

46 4. A grocer has two kinds of nuts. One costs $5 / kg and another cots $4.20 / kg. How many kilograms of each type of nut should be mixed in order to get 60 kg of mixture worth $4.80 / kg? Number of kg X Price per kg = Cost Nut 1 n Nut 2 Mixture 5. A chemist has 80 ml of a solution that is 70% salt. How much water should he add to make a solution that is 40% salt? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution 6. If 800 ml of a juice drink is 10% grape juice, how much grape juice should be added to make a drink that is 20% grape juice? Total Amount X Percent Acid = Amount of Acid Original Solution g Water New Solution 45

47 7. How many liters of water must be added to 70 L of a 40% acid solution in order to produce a 28% acid solution? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution 8. How many ml of pure water must be added to 60 ml of a 20% salt solution to make a 12% salt solution? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution 9. A nurse has 100 ml of a solution that is 10% salt. How much sterile water must be added to make an 8% salt solution? Total Amount X Percent Acid = Amount of Acid Original Solution Water w New Solution 46

48 Algebra 1 RATE TIME DISTANCE PROBLEMS Name Solve by completing the chart. Show all work. 1. Two jets leave Ontario at the same time, one flying east at a speed of 20km / h greater than the other, which is flying west. After 4 hours, the planes are 6000 km apart. Find their speeds. Rate X Time = Distance East Bound West Bound r 2. Two camper vans leave Arrowhead Lake at the same time, one traveling north at a speed of 10 km / h faster than the other, which is traveling south. After 3 hours, the camper vans are 420 km apart. Find their speeds Rate X Time = Distance South Bound r North Bound 3. Two cars traveled in opposite directions from the same starting point. The rate of one car was 10 km less than the rate of the other. After 4 hours the cars were 600 km apart. Find the rate of each car. Rate X Time = Distance South Bound r North Bound 4. A car started out from Memphis toward Little Rock at the rate of 60 km / h. A second car left from the same point 2 hours later and drove along the same rout at 75 km / h. How long did it take the second car to overtake the first car? Rate X Time = Distance Car 1 Car 2 t 47

49 5. A tourist bus leaves Richmond at 1:00 pm fro New York City. Exactly 24 minutes later, at truck sets out in the same direction. The tourist bus moves at a steady 60 km/ h. the truck travels at 80 km / h. How long does it take the truck to overtake the tourist bus? Rate X Time = Distance Bus Truck t 6. Exactly 20 minutes after Alex left home, his sister, Alison set out to overtake him. Alex drove at 48 mph and Alison drove at 54 mph. How long did it take Alison to overtake Alex? Rate X Time = Distance Alex Alison t 7. The McLeans drove from their house in Dayton at 75 km / h. When they returned, the traffic was heavier and they drove at 50 km / h. If it took them 1 hour longer to return than to go, how long did it take them to drive home? Rate X Time = Distance To Go Come Home t 8. It takes a plane one hour less to fly from San Diego to New Orleans at 600 km / h than it does to return at 450 km / h. How far apart are the cities? Rate X Time = Distance San Diego d New Orleans 48

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