Mathematics 9709 · AS & A Level · Sampling and estimation

Sampling and estimation — practice question

A simple random sample of 250 residents of Barapet was selected. It was discovered that 78 of these residents owned a BETEC phone.
(a)[3]

Calculate an approximate $98\%$ confidence interval for the share of people living in Barapet who own a BETEC phone.

(b)[1]

Manjit says that over $40\%$ of Barapet’s residents own a BETEC phone. Use your answer to part (a) to assess this claim.

Worked solution & mark scheme

This 4-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Application of the confidence interval formula $\frac{78}{250}\pm z\sqrt{\frac{\frac{78}{250}(1-\frac{78}{250})}{250}}$” …

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