Question

A simple random sample of 90 items from a population with = 9 resulted in a sample mean of 38.

If required, round your answers to two decimal places.

a. Provide a 90% confidence interval for the population mean.
to

b. Provide a 95% confidence interval for the population mean.
to

c. Provide a 99% confidence interval for the population mean.
to

Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. A sample of 55 weekly reports showed a sample mean of 19.5 customer contacts per week. The sample standard deviation was 5.9. Provide 90% and 95% confidence intervals for the population mean number of weekly customer contacts for the sales personnel.

90% Confidence interval, to 2 decimals:

( , )

95% Confidence interval, to 2 decimals:

( , )

Answer 1

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