Printable · GCSE Foundation · ages 14-16

Sampling and inference about populations worksheet — GCSE Foundation

Fifteen questions on "sampling and inference about populations" — DfE statement S1. Print it, or print three versions so neighbours cannot copy by letter; the key gives the letter for each version.

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Sampling and inference about populations worksheet — GCSE Foundation

Maths · GCSE Foundation · S1 · Sampling and inference about populations · 15 questions

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1.A school has 1,000 pupils. A student wants to estimate how many of them walk to school, so she asks 8 pupils in her own class. She says her sample is large enough to give a reliable estimate for the whole school. Is she right? Give a reason for your answer.
(a)Yes — any sample size is equally reliable.
(b)No — because the sample was not taken online.
(c)No — 8 from one class is too small to represent the school.
(d)Yes — because 8 is more than half of her class.
2.A sports centre in Ipswich has 2,000 members. It wants to know what its members think of its opening hours, so it asks a random sample of 100 of them. Write down what the population is in this survey.
(a)Everybody who lives in Ipswich.
(b)All 2,000 members of the sports centre.
(c)The members who say they are unhappy with the opening hours.
(d)The 100 members who were asked.
3.Priya wants to find out the favourite sport of the 900 pupils at her school. She asks 5 pupils, chosen at random. Give a reason why her sample may not give a reliable result.
(a)5 pupils are far too few to represent 900 pupils
(b)A sample must hold at least half of the population
(c)5 pupils were not chosen at random from the 900
(d)The 5 pupils may each name a different sport
4.A school posts a questionnaire about school dinners to the families of all 200 pupils. Only 30 families send theirs back, and 27 of those 30 say they are unhappy with school dinners. Give a reason why this result may not represent all 200 families.
(a)Postal surveys always have low response rates.
(b)The 27 unhappy replies show most families are unhappy.
(c)The families who replied were picked at random by the school.
(d)Only families with strong feelings bothered to reply.
5.A factory made 3,000 phone cases last week. Shift A checked a random sample of 100 cases and found that 34 were scratched. Shift B checked a different random sample of 50 cases and found that 21 were scratched. Using the COMBINED results from both shifts, work out an estimate for the number of scratched cases made last week.
(a)1140
(b)1020
(c)1260
(d)1100
6.There are 10,000 pupils in a city. A researcher picks a sample of 500 of them by drawing names at random from a list of every pupil in the city. Give the reason why this method gives a representative sample.
(a)Because the pupils most willing to help are chosen
(b)Because the sample must be exactly 5% of the population
(c)Because every pupil has an equal chance of being picked
(d)Because 500 is large enough however they are chosen
7.A company makes 50,000 light bulbs a day and wants to check how long they last before they fail. Testing a bulb to find out how long it lasts destroys it. Give a reason why the company should test a sample of bulbs rather than every bulb it makes.
(a)A sample is always more accurate than a census.
(b)It is against the law to test every bulb made.
(c)Testing every bulb uses too much electricity.
(d)Testing destroys bulbs, so testing all leaves none to sell.
8.A charity shop in Bath holds 2,000 books. Volunteer A checks a random sample of 50 books and finds 35 paperbacks. Volunteer B checks a different random sample of 50 books and finds 31 paperbacks. Work out the estimate each sample gives for the whole stock, and write down what the shop should do next.
(a)1,400 and 1,240, so combine the samples for one estimate
(b)1,400 and 1,240, so keep 1,400 as the larger estimate
(c)1,400 and 1,240, so one volunteer must have miscounted
(d)1,750 and 1,550, so the larger estimate must be right
9.A school has 1200 pupils. A teacher wants to take a random sample of 60 of them. Write down which of these methods gives a random sample.
(a)Drawing 60 names at random from a list of all 1200 pupils
(b)Asking the 60 pupils nearest the door at the first break
(c)Asking every pupil in two of the Year 10 classes
(d)Asking the 60 pupils who volunteer to take part
10.A random sample of 50 pupils at a school were asked whether they prefer sport to music. 30 of the 50 pupils said they prefer sport. The school has 500 pupils altogether. Work out an estimate for the number of the 500 pupils who prefer sport.
(a)150 pupils
(b)200 pupils
(c)60 pupils
(d)300 pupils
11.A school has 1,500 pupils. The head teacher takes a random sample of 150 of them from the school register and asks how long they spend on homework. Rory says the sample is too small for the result to mean anything. Is Rory right? Give a reason for your answer.
(a)No, 150 pupils are a tenth of the school, chosen at random
(b)Yes, 150 pupils cannot be picked at random from 1,500
(c)No, a random sample always gives the exact school figure
(d)Yes, only asking all 1,500 pupils could show anything
12.A factory makes 4,000 light bulbs a day. In a random sample of 80 of one day's bulbs, 3 were faulty. Work out an estimate for the number of faulty bulbs the factory makes in a day.
(a)150 bulbs
(b)240 bulbs
(c)120 bulbs
(d)50 bulbs
13.In a random sample of 40 pupils at a school, 6 are left-handed. The school has 900 pupils. Work out an estimate for the number of left-handed pupils in the school.
(a)6
(b)135
(c)22.5
(d)5400
14.A sports club has 300 women members and 200 men members, 500 members in total. The club committee wants to choose a sample of 40 members that is in proportion to the club's membership. Work out how many women should be in the sample.
(a)16
(b)20
(c)30
(d)24
15.A factory makes a batch of 4,000 circuit boards. It checks a random sample of 50 boards and finds that 4 are faulty. The factory will scrap the whole batch if the estimated number of faulty boards in the batch is more than 250. Should the factory scrap the batch?
(a)No — with an estimate of 80, below the 250 limit.
(b)No — only 4 faulty in the sample, far fewer than 250.
(c)Yes — with an estimate of 320, above the 250 limit.
(d)Yes — with an estimate of 500, above the 250 limit.

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