# computed the sample mean to be 100.

A) A statistics practitioner took a random sample of 50 observations from a population whose standard deviation is 25 and computed the sample mean to be 100. Estimate the population mean with 90% confidence.

b) Repeat part a using a 95% confidence level

c) Repeat part a using a 99% confidence level

d) Describe the effect on the confidence interval estimate of increasing the confidence level.

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#### Solution Preview

Please see attached file.

Confidence interval - mean

90% confidence level

100 mean

25 std. dev.

50 n

1.677 t (df = 49)

5.928 half-width

105.928 upper ...

#### Solution Summary

This solution calculates the population mean with 90%, 95% and 99% confidence level and explains the effect of increasing the confidence level percentage.

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