Question

You measure 25 textbooks' weights, and find they have a mean weight of 63 ounces. Assume the population standard deviation is 5.5 ounces. Based on this, construct a 90% confidence interval for the true population mean textbook weight.

Give your answers as decimals, to two places

Answer 1

Solution :

Given that,

Sample size = n = 25

Z/2 = 1.645

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

= 1.645 * (5.5 / 25)

Margin of error = E = 1.81

At 90% confidence interval estimate of the population mean is,

- E < < + E

63 - 1.81 < < 63 + 1.81

61.19 < < 64.81

(61.19 , 64.81)