Question

You measure 27 textbooks' weights, and find they have a mean weight of 40 ounces. Assume the population standard deviation is 13 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,

Z_/2 = 1.645

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

= 1.645 * (13 / 27)

= 4.12

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

- E < < + E

40 - 4.12 < < 40 + 4.12

35.88 < < 44.12

(35.88 , 44.12)