The weights of running shoes are normally distributed with a population standard deviation of 3 ounces and an unknown population mean. if a random sample of 23 running shoes is taken and results in a sample mean of 18 ounces, find a 90% confidence interval for the population mean.

Step-by-step explanation:

Given : Level of significance :

Then , significance level :

Since , sample size : , which is small sample (n<30) so the test applied here is a t-test.

Sample mean :

Standard deviation:

Degree of freedom=

Using t-distribution table , Critical value :

The confidence interval for population mean is given by :-

Hence,  a 90% confidence interval for the population mean=

the answer is 510

step-by-step explanation:

15 • 13 = 195

15 • 12 = 180

15 • 5 = 75

12 • 5 = 60

195 + 180 = 375

375 + 75 = 450

450 + 60 = 510