Question

You measure 26 textbooks' weights, and find they have a mean weight of 67 ounces. Assume the population standard deviation is 11.5 ounces. Based on this, construct a 90% confidence interval for the true population mean textbook weight. Give your answers as decimals, to two places < μ

Answer 1

The formula for calculating the 90% confidence interval for the true population mean textbook weight us given by-

Given:

sample mean,

sample size,

population standard devistion,

Now we have to calculate the 90% confidence interval, then the for 90% confidence level is

So, the 90% confidence interval for the true population mean weight of the texrbook is calculated as

Hence, we are 90% confident that the true population mean weight of the textbook is lie between and it can also be written as