Question

You measure 34 textbooks' weights, and find they have a mean weight of 73 ounces. Assume the population standard deviation is 11.4 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,

Point estimate = sample mean = = 73

Population standard deviation = = 11.4

Sample size = n = 34

Z_/2 = 1.645

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

= 1.645 * (11.4 / 34)

= 3.22

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

- E < < + E

73 - 3.22 < < 73 + 3.22

69.78 < < 76.22

(69.78 , 76.22)