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

MathsUKwww.geekhero.co.uk

1.Isla wants to find out the favourite television programme of the pupils at her school. She asks only her own close group of friends. Write down what is wrong with her sample.
(a)It is fine, as everyone she asked goes to her school
(b)It is too small, though it was picked at random
(c)It is not representative, as she picked her own friends
(d)It is too large, so she gets more replies than she needs
2.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.
3.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
4.A town council wants to find out about the eating habits of the people who live in the town. It asks only the members of a local sports club. Give a reason why this sample is biased.
(a)The club has more members than the council needs
(b)The members were picked at random, so some will not reply
(c)Club members probably eat differently from most people
(d)Everyone asked lives in the town, so all are covered
5.A council in Leeds wants to know what local people think about letting shops stay open later in the evening. It rings landline telephone numbers between 10 am and 2 pm on a Tuesday. Write down which group is most likely to be under-represented in the sample, and give a reason for your answer.
(a)Children, as most of them are at home at that time
(b)Unemployed people, as most of them are out at that time
(c)Retired people, as most of them are at work then
(d)Full-time workers, as most are at work at that time
6.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.
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 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
9.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
10.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
11.A pupil writes this question for a school survey: “Do you agree that learning matters and that we should be set more homework?” Write down what is wrong with the survey question.
(a)It uses long words that most pupils will not understand
(b)It is too short for the reader to see the point
(c)It is fine, as it can be answered yes or no
(d)It asks two things at once and invites agreement
12.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
13.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
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 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

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