Sales personnel for skillings distributors submit weekly reports listing the customer contacts made during the week. a sample of 68 weekly reports showed a sample mean of 17.5 customer contacts per week. the sample standard deviation was 4.2. provide a 90% confidence interval for the population mean number of weekly customer contacts for the sales personnel. (round your answers to two decimal places.)

(16.65, 18.35)

Step-by-step explanation:

By considering the given information , we have

mm

s=  4.2 mm

n= 68

Significance level

Since population standard deviation is not given ,

Formula :

Confidence interval for population mean is given :-

, where n = sample size.

= Two-tailed t-value for significance level of and degree of freedom df= n-1.

= sample standard deviation.

Two-tailed t-value for significance level of and degree of freedom df= 67:

95% Confidence interval for population mean:

Hence, the 90% confidence interval for the population mean number of weekly customer contacts for the sales personnel. = (16.65, 18.35)

which expression represents the approximate length of bc?

step-by-step explanation:

the first one is x^2+2x+2

the second one is x^2+4

the last one is x^2-4x+8