A provincial politician would like to determine the average amount earned during summer employment by the provinces teenagers during the past summer’s vacation period. She wants to have 95% confidence that the sample mean is within $25 of the actual population mean. Bases on past studies, she knows the amount earned is normally distributed with a standard deviation of $400. What sample size must she take?

asked by Maria Elizabeth

12 years ago

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1 answer

95% = mean ± 1.96 SEm

SEm = SD/√n

25 = 1.96 * 400/√n

Solve for n.

answered by PsyDAG

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Question

A provincial politician would like to determine the average amount earned during summer employment by the provinces teenagers during the past summer’s vacation period. She wants to have 95% confidence that the sample mean is within $25 of the actual population mean. Bases on past studies, she knows the amount earned is normally distributed with a standard deviation of $400. What sample size must she take?

1 answer

95% = mean ± 1.96 SEm

SEm = SD/√n

25 = 1.96 * 400/√n

Solve for n.

Ask a New Question or answer this question.

PsyDAG · Answer

95% = mean ± 1.96 SEm SEm = SD/√n 25 = 1.96 * 400/√n Solve for n.