Question

Assume that a sample is used to estimate a population mean μμ. Find the 95% confidence interval for a sample of size 73 with a mean of 38.6 and a population standard deviation of 13.9. Enter your answer as an open-interval (i.e., parentheses) accurate to 3 decimal places.

95% C.I. =

The answer should be obtained without any preliminary rounding.

Answer 1

Sample size ,n = 73

Mean = u = 38.6

standard deviation,s =  13.9

Z score value at 95% CI = 1.960

Confidence Interval = u Z*s/

Upper limit = u + Z*s/ = 38.6 + 1.960*13.9/ = 41.789

Lower limit = u - Z*s/ = 38.6 - 1.960*13.9/ = 35.411

95% C.I. = (35.411 , 41.789 )