Question

Assume that a sample is used to estimate a population mean μ . Find the 80% confidence interval for a sample of size 508 with a mean of 42.7 and a standard deviation of 20.4. Enter your answers accurate to four decimal places. Confidence Interval

Answer 1

Solution :

Given that,

Z_/2 = 1.28

Margin of error = E = Z_/2* ( /n)

= 1.28 * (20.4 / 508)

= 1.1585

At 80% confidence interval estimate of the population mean is,

- E < < + E

42.7 - 1.1585 < < 42.7 + 1.1585

41.5415 < < 43.8587

(41.5415 , 43.8587)