GCSE · Sampling

Populations & samplesExam-style questions

What a population and a sample are and why we sample at all; why a representative sample matters more than a big one; and the two calculations that earn the marks — scaling a sample up to estimate a population total (including capture–recapture and its assumptions) and sharing a stratified sample out in proportion.

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11 questions · GCSE (Higher) level · mark scheme and worked solution on each · no sign-up to try

DifficultyAllLevel 1Level 2Level 3Level 4Level 5
  1. 1
    Priya is estimating the number of frogs in a nature reserve.

    She catches 6060 frogs, marks each one and releases them.

    Later she catches 4545 frogs and uses her results to estimate that there are 300300 frogs in the reserve.

    (a) Work out how many of the 4545 frogs in Priya's second catch were marked.

    (b) In fact the marked frogs stayed close to the pool where Priya released them, and Priya made her second catch at that same pool.

    Explain what effect this has on her estimate of 300300.
    Level 5 · 4 marksTry it
  2. 2
    A sports club has 840840 members. Each member belongs to exactly one section.
    SectionNumber of members
    Football288288
    Netball168168
    Athletics240240
    Swimming144144
    A stratified sample of the members is taken. The sample contains 1414 members from the Netball section.

    (a) Work out the total number of members in the sample.

    (b) Work out how many members from the Athletics section are in the sample.

    (c) Of the members in the sample, 4242 said they train more than twice a week.

    Use this to estimate the number of the 840840 club members who train more than twice a week.
    Level 5 · 6 marksTry it