please answer with detail working please answer in text using Excel or word only

#8. Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. (a). A sample of 49 weekly reports showed a sample mean of 18.35 customer contacts per week. The sample standard deviation was 6.95. Provide 80% confidence intervals for the population mean number of weekly customer contacts for the sales personnel. (5 points) (b). A sample of 4 weekly reports showed a sample mean of 25.38 customer contacts per week. The sample standard deviation was 4.15. At 90% confidence, what is the margin of error? (5 points)