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In: Statistics and Probability

An accounting firm does a study to determine the time needed to complete one person's tax...

An accounting firm does a study to determine the time needed to complete one person's tax forms. It randomly surveys 40 people. The sample mean is 17.4 hours and the sample standard deviation is 6.2 hours. Based on this data, construct a 95% confidence interval for the time to complete one person's answer. Round to nearest hundredth of an hour

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Expert Solution

Solution :

Given that,

= 17.4

= 6.2

n = 40

At 95% confidence level the z is ,

= 1 - 95% = 1 - 0.95 = 0.05

/ 2 = 0.05 / 2 = 0.025

Z/2 = Z0.025 = 1.96

Margin of error = E = Z/2* ( /n)

= 1.96 * (6.2 / 40)

= 1.92

At 95% confidence interval estimate of the population mean is,

- E < < + E

17.4 - 1.92 < < 17.4 + 1.92

15.48< < 19.32

(15.48, 19.32)

orchestra answered 2 years ago
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