Question

Sales personnel for Skillings Distributors submit weekly reports listing the customer contacts made during the week. A sample of 85 weekly reports showed a sample mean of 17.5 customer contacts per week. The sample standard deviation was 5.1. 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

given data are :-

sample mean () = 17.5

sample size (n) = 85

sample sd (s) = 5.1

df= (n-1) = (85-1) = 84

t critical value for df=84,alpha=0.10,both tailed test be:-

the 90% confidence interval for the mean be:-

b).t critical value for df=84,alpha=0.05,both tailed test be:-

the 95% confidence interval for the mean be:-

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