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Interpret simulated sampling distributions and interval variation

Question 1 of 8

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A transport survey records whether a commuter uses public transport for a trip

The population proportion for commuters who use public transport for the trip is \(p=\frac{1}{3}\)

A simulation took \(8\) random samples of \(n=20\) commuters. The success count and sample proportion for each sample are shown

\[\widehat p=\frac{X}{n}\]
Simulated sample proportions
RunSuccess countSample proportion
Run 1\(3\)\(\frac{3}{20}\)
Run 2\(5\)\(\frac{1}{4}\)
Run 3\(10\)\(\frac{1}{2}\)
Run 4\(9\)\(\frac{9}{20}\)
Run 5\(5\)\(\frac{1}{4}\)
Run 6\(3\)\(\frac{3}{20}\)
Run 7\(9\)\(\frac{9}{20}\)
Run 8\(5\)\(\frac{1}{4}\)
Dot plot of the simulated sample proportions in percentage points. The plotted values are 15%, 25%, 50%, 45%, 25%, 15%, 45%, 25%. Values: 15, 25, 50, 45, 25, 15, 45, 25.15253545Sample proportion (%)
Dot plot of the simulated sample proportions

A second simulation used the same population proportion and the same number of samples, but its sample size was \(n=10\)

Two simulated sample sizes
RunSimulation A, n = 20Simulation B, n = 10
Run 1\(3: \frac{3}{20}\)\(2: \frac{1}{5}\)
Run 2\(5: \frac{1}{4}\)\(3: \frac{3}{10}\)
Run 3\(10: \frac{1}{2}\)\(1: \frac{1}{10}\)
Run 4\(9: \frac{9}{20}\)\(6: \frac{3}{5}\)
Run 5\(5: \frac{1}{4}\)\(6: \frac{3}{5}\)
Run 6\(3: \frac{3}{20}\)\(3: \frac{3}{10}\)
Run 7\(9: \frac{9}{20}\)\(6: \frac{3}{5}\)
Run 8\(5: \frac{1}{4}\)\(3: \frac{3}{10}\)
(a)1 mark

Which statement identifies the centre of the simulated sampling distribution?

(b)1 mark

Compare the spread produced by the two sample sizes