Question

The Hiatus retail outlet takes a random sample of 25 customers from a segment population of 1,000 with a mean average transaction size of $80 normally distributed with a known population standard deviation of $20 per transaction.

A. Find the confidence intervals for 1 if the population is not known and the sample standard deviation is $23 per transaction.

B. Find the minimum sample size required for 2 if the population is not known and a sample standard deviation is $34.

PLEASE HELP!!!!!

Answer 1

In both cases without loss of generality we can assume 95% confidence.

A. The 95% confidence interval of the population mean transaction size = [, ], where, = 80, s = 23, n = 25

Thus, 95% C.I. = [80 - 9.4944, 80 + 9.4944] = [70.5056, 89.4944]

B. Need information on the margin of error to determine the sample size needed.

We know, = Margin of error