Samples and Surveys pp

Transcription

1 LESSON 4-1 Samples and Surveys pp Vocabulary population (p. 174) sample (p. 174) biased sample (p. 174) random sample (p. 175) systematic sample (p. 175) stratified sample (p. 175) Additional Examples Example 1 Identify the population and the sample. Give a reason why the sample could be biased. A. A record store manager asks customers who make a purchase how many hours of music they listen to each day. Population Sample Possible Bias Customers who make a purchase might be more in music than others in the store. 67 Holt Pre-Algebra

2 LESSON 4-1 CONTINUED Example Identify the sampling method used. A. In a county survey, Democratic Party members whose names begin with the letter D are chosen. The is to survey members whose names begin with D. B. A telephone company randomly chooses customers to survey about its service. Customers are chosen by. Try This 1. Identify the population and the sample. Give a reason why the sample could be biased. People attending a baseball game were asked if they support the construction of a new stadium in the city. Population Sample Possible Bias People that attend a baseball game are more likely to the construction of a new stadium.. Identify the sampling method used. In a county survey, families with 3 or more children are chosen. 68 Holt Pre-Algebra

3 LESSON 4- Organizing Data pp Vocabulary stem-and-leaf plot (p. 179) back-to-back stem-and-leaf plot (p. 180) Additional Examples Example 1 Use the given data to make a table. Jack timed his bus rides to and from school. On Monday, it took 7 minutes to get to school and 9 minutes to get home. On Tuesday, it took 5 minutes and 9 minutes, respectively, and on Wednesday, it took 8 minutes and 7 minutes. Example List the data values of the stem-and-leaf plot Key: 1 means 1 The data values are 69 Holt Pre-Algebra

4 LESSON 4- CONTINUED Example 3 Use the given data to make a stem-and-leaf plot. Top Speeds of Animals (mi/h) Cheetah 64 Elk 45 Wildebeest 61 Coyote 43 Lion 50 Gray Fox 4 Speeds range from 4 to 64 so stems are 4 to 6. Example 4 Use the given data to make a back-to-back stem-and-leaf plot. U.S. Representatives for Selected States, 1950 and 000 IL MA MI NY PA Holt Pre-Algebra

5 LESSON 4- CONTINUED Try This 1. Use the given data to make a table. Jill timed herself jogging to the park and back home. On Monday she ran to the park in 1 minutes then back home in 14 minutes, on Tuesday it took her 13 and 15 minutes, respectively, and on Wednesday, it took her 11 minutes and 13 minutes.. List the data values of the stem-and-leaf plot Key: 3 means 3 3. Use the given data to make a stem-and-leaf plot. Percent of Persons under 18 years old, year 000 Florida California Texas Arizona New York Alaska 3% 7% 8% 7% 5% 30% 4. Use the given data to make a back-to-back stem-and-leaf plot. U.S. Representatives for Selected States, 1950 and 000 IL MA MI NY PA Holt Pre-Algebra

6 LESSON 4-3 Measures of Central Tendency pp Vocabulary mean (p. 184) median (p. 184) mode (p. 184) outlier (p. 185) Additional Examples Example 1 Find the mean, median, and mode of the data set. A. 16, 5, 31, 14, 14, 18 mean: the values Divide by, the number of values. median: values 3 values the values. the two middle values. mode: The value occurs two times. 7 Holt Pre-Algebra

7 LESSON 4-3 CONTINUED B. 83, 45, 19, 33 mean: the values. 180 Divide by, the number of values. median: values values the values. Average the two values. mode: other. occurs more than any Try This 1. Find the mean, median, and mode of the data set. 4, 31, 1, 18, 4, 73 Holt Pre-Algebra

8 LESSON 4-4 Variability pp Vocabulary variability (p. 188) range (p. 188) quartile (p. 188) box-and-whisker plot (p. 189) Additional Examples Example Use the given data to make a box-and-whisker plot. 1, 5, 15, 13, 17, 19, 19, 1 Step 1. Order the data and find the smallest value, first quartile, median, third quartile, and largest value. smallest value: first quartile: median: third quartile: 74 Holt Pre-Algebra

9 LESSON 4-4 CONTINUED largest value: Step. Draw a number line and plot a point above each value from Step Step 3. Draw the box and whiskers Try This 1. Find the range and the first and third quartiles for the data set. 45, 31, 59, 49, 49, 69, 33, 47. Use the given data to make a box-and-whisker plot. 31, 3, 33, 35, 6, 4, 31, Holt Pre-Algebra

10 LESSON 4-5 Displaying Data pp Vocabulary bar graph (p. 196) frequency table (p. 196) histogram (p. 196) line graph (p. 197) Additional Examples Example 1 Organize the data into a frequency table and make a bar graph. The following data set reflects the number of hours of television watched every day by members of a sixth-grade class: First, organize the data into a table. The times each value occurs. is the number of Television Viewing by Sixth-Graders The frequencies are the the bars in the bar graph. of 76 Holt Pre-Algebra

11 LESSON 4-5 CONTINUED Example Jimmy surveyed 1 children to find out how much money they received from the tooth fairy. Use the data to make a histogram First, make a intervals of $1.00. Then make a table with Money Given by the Tooth Fairy. Example 3 Make a line graph of the given data. Use the graph to estimate Mr. Yi s salary in 199. Create ordered pairs from the data in the table and plot them on a grid. Connect the points with lines. You can estimate the salary in 199 by finding the point on the line between 1990 and 1995 that corresponds to 199. Year Salary ($) , , , ,000 Mr. Yi s Salary Mr. Yi s 199 salary was about $. 77 Holt Pre-Algebra

12 LESSON 4-5 CONTINUED Try This 1. Organize the data into a frequency table and make a bar graph. The following data set reflects the number of laptop computers that are repaired by Mike the technician in one week. (Each number reflects one day.) Tonya surveyed 14 children at an after school day care to find out how many hours they spend there. Use the data to make a histogram. :00 1:40 3:00 0:30 1:00 1:30 :30 0:30 :45 1:00 :00 1:35 1:30 3:00 78 Holt Pre-Algebra

13 LESSON 4-6 Misleading Graphs and Statistics pp Additional Examples Example 1 Explain why each graph is misleading. A. Stock Value The graph suggests that the stock will continue to increase through, but there s no way to foresee the. B. School Play Because the first interval of the scale goes from Ticket Sales to, the bar 10 Tickets Sold th 7th Grade 8th make it appear that the sixth grade sold about times as many tickets as either of the other two grades. In fact, the sixth grade sold only about more. Example Explain why each statistic is misleading. A. Sam scored 43 goals for his soccer team during the season, and Jacob scored only. Although Jacob scored only goals, he may have played most of his time on. 79 Holt Pre-Algebra

14 LESSON 4-6 CONTINUED B. Four out of five dentists surveyed preferred UltraClean toothpaste. This statement does not give the size or state what UltraClean toothpaste was with. C. Shopping at Save-a-Lot can save you up to $100 a month! The words save up to $100 mean that the is $100, but there is no you can save that you will save that amount. Try This 1. Explain why the graph is misleading. Preferred Juice Flavors Grape Cherry Apple. Explain why the statistic is misleading. The total revenue for bathing suits sold in May at Worthman s Florida stores is $50,000. The total revenue for bathing suits sold in May at Worthman s North Dakota stores is $10, Holt Pre-Algebra

15 LESSON 4-7 Scatter Plots pp Vocabulary scatter plot (p. 04) correlation (p. 04) line of best fit (p. 04) Additional Examples Example 1 Use the given data to make a scatter plot of the weight and height of each member of a basketball team. Height (in.) Weight (lb) Weight (lb) Height (in.) The points on the scatter plot are ( ), ( ), ( ), ( ), and ( ). 81 Holt Pre-Algebra

16 LESSON 4-7 CONTINUED Example Do the data sets have a positive, a negative, or no correlation? A. The size of a jar of baby food and the number of jars of baby food a baby will eat. correlation: The food in each jar, the number of jars of baby food a baby will eat. B. The speed of a runner and the number of races she wins. correlation: The the runner, the races she will win. Try This 1. Use the given data to make a scatter plot of the weight and height of each member of a soccer team. Height (in) Weight (lb) Weight Height. Does the data set have a positive, a negative, or no correlation? Your grade point average and the number of A s you receive. 8 Holt Pre-Algebra

17 Chapter 4 Picture Cube box-and-whisker plot bar graph histogram line graph scatter plot stem-and-leaf plot Directions 1. Draw an example of each term on the net of the cube.. Cut out the net. 3. Fold along all dotted lines, and place glue tabs to the inside of the cube. 4. Join the common edges, and tape or glue the tabs in place. Developed in cooperation with The Bag Ladies. 83 Holt Pre-Algebra