PiXL AQA Style Pre Paper 2F Practice Answers

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1 PiXL AQA Style Pre Paper 2F Practice Answers This set of answers is not a conventional marking scheme; while it gives a basic allocation of marks, its main purpose it to help students understand how to do each question and how they can avoid making mistakes. As such, its format is rather different from that of a normal mark scheme. The following guidance is adapted from that issued by AQA Types of mark M A B Method marks are awarded for a correct method which could lead to a correct answer. Accuracy marks are awarded when following on from a correct method. It is not necessary to always see the method. This can be implied. Marks awarded independent of method. Working out Usually, if the question asks students to show working, marks are not awarded to students who show no working. As a general principle, where the questions does not ask students to show working, a correct answer is awarded full marks. However, if the answer is incorrect, students can still obtain method marks, assuming that they show some valid working out. An incorrect answer with no working out is always awarded zero. Premature approximation Rounding off too early can lead to inaccuracy in the final answer. This is normally penalised by 1 mark = Most scientific calculators will calculate operations in the correct order if the calculation is entered correctly. Here, is calculated first, then the result subtracted from Any valid method 135 This is here as a reminder not to put the times directly into your calculator gives 2.55, but the film is not 2 hours and 55 minutes long. You are asked for the answer in minutes; 2 hours 15 minutes is right, but not what you are asked for, so A0.

2 6 (a) Any valid method to divide the money. Adam: 38 Brenda: 20 Caitlin: 216 Either 1 of 38 = 96 or 2 5 of 20 = 96 correctly worked out. Must see somewhere for this. Both give Dave 96 each Both must be seen with correct working out. 6 (b) or % ( %) Must be correct. If you got a partly correct answer to (a), you could get here for a valid method to find a percentage of 80 for your number. 7 (a) Most scientific calculators will calculate operations in the correct order if the calculation is entered correctly. Here, is calculated first, then the result added to (b) (=70.56) Take square root of your answer to ; award for the method, even if is wrong % seen Smallest possible percentage for Mrs Green Works out 38.5% of Actual value of 38.5% of 258 is 99.8, so smallest possible number of people is 995. Award M0 A0 if 39% of 258 = 1008 is calculated At least two of these amounts must be correct All three amounts will be correct if you get this mark Not 506.0p or days = 96 hours Speed = distance time 00 kph

3 11 (a) b 2 = 1936 b = 11 (b) q 3 = 33 From 2q 3 = 686, divide by 2 before taking the cube root. q = 7 12 Any valid method to find 8% of 95 Remember that you have a calculator, so use it; don t spend your time doing 10%, 5%, 1%, etc. Total cost is Must see and an attempt to add to the Division by 12 of your previous answer..55 Correct answer only for. 13 Uses Pythagoras for AC Must see AC 2 = with numbers substituted into the formula; just writing a 2 + b 2 = c 2 or similar isn t enough for a mark. AC = Uses square root to get AC; must see cm The final 0 must be present for 1 decimal place. 1 Either = and = or = 53.0 and = (other variants possible) 1.5 l box ticked Either divide the price by the quantity (to find the cost of 1 litre or 1 ml) or divide the quantity by the price (to find the quantity per 1 or 1p). There are several alternatives (ml or litres, 1 or 1p); two are given here. Both divisions must be correct for the second mark. As well as ticking the box, write down your conclusion from the calculations. Of course, ticking a box (even the correct one) with no working out will get you no marks. 15 π or π You must learn the formulae for the area and circumference of a circle. seen This is a quarter circle, so divide the whole circle by. 52.8cm 2 16 sin 23 = cos 67 cos 58 = cos ( 58 ) These two should be ticked. Other indications (eg T and F for true and false, but why bother not using the tick? Make sure your calculator is set in degrees litres = gallons or 100 km = 62.5 miles seen 62.5 miles (your number of miles) (your number of gallons) 2. mpg Correct answer, rounded sensibly.

4 18 (a) Sight of an attempt to find and an attempt to divide the result by will get you the method mark. Be very careful entering negative powers for standard form. Make sure you know how to use the standard form key on your calculator. Correct answer. Other roundings accepted (b) Nitrogen This is the only gas with a mass bigger than Keith s total. 18 (c) % Add to to find the total mass (or just add all five masses together from scratch) ( ) (total you found before) % or 0.85 used Correct answer. Other roundings accepted. The sale price is 85% of the original; do not work out 15% of the sale price or.8 seen If 85% is 08, this will work out what 1% is, from which you can find 100% (a) sin50 =? 6? = 6 sin50 Not enough just to identify trigonometry here; you must use the correct trigonometric ratio (sin, cos or tan) and make a fraction. You would be let off a small mistake here, if your intention was clear. For the second mark there won t be any mistakes in your working out..6m (.596 m) Round your answer to a sensible level of accuracy. 20 (b) cos(angle) = 2 6 Not enough just to identify trigonometry here; you must use the correct trigonometric ratio (sin, cos or tan) and make a fraction with the numbers. angle = which is pretty close to 70 The ladder is safe so remember to tick the ladder is safe box. As ever, no working here means no marks.

5 21 (a) After a 3% reduction, there is 97% left. 21 (b) (i) seen, or 6210, or or or 210 or or = or = Any correct method to find interest for one of the two years - this may be implied by sight of any correct amount of interest, or the value after one year. Correct answer seen, or 6900, or = 180 and = 900 Works out the value of 6000 invested for 5 years at 3% simple interest, or writes down multiplier for 3% simple interest over 5 years. 21 (b) (ii) Any method to increase by 2.5% at least once = or = Very similar to the and marks for part (b) (i). There is no need to round the amounts (although rounding to the nearest penny would seem sensible). It is, however, possible to make the comparison without using the 6000 at all. The multiplier for 3% simple interest over 5 years is 1.15 (see above); the multiplier for the compound interest is = , which is bigger than This would give full marks. Compound interest greater Correct answer; you must, of course, have complete, correct working out. 22 (a) 30 < t = = 53 Median is higher than (b) Mid values seen Use the middle of each interval. Should be 7.5, 22.5, 37.5 and 52.5, but 8, 23, 38 and 53 would be accepted (had the question said that the times were to the nearest minute, they would have been correct anyway). If your method is right, you will be let off a small mistake here. Again, use of 8, 23, 38 and 53 for the mid values would be accepted. Whatever you get for the total time must be divided by the number of contestants. With 8, 23, 38 and 53, this would be minutes Could be rounded to 32. (32.6 with 8, 23, 38 and 53 ) 23 3 π Use the formula to find the volume of the object. Volume is m (whatever you got for the volume) 870 kg/m g/cm 3 and The object will float in water but not in oil box ticked. Divide mass by volume to find density Correct answer; you must have complete, correct working out for this last mark.