7. The heights (in inches) of adult males in the United States are believed to be Normally distributed with mean . The average height of a random sample of 25 American adult males is found to be x= 69.72
inches, and the standard deviation of the 25 heights is found to be s=4.15 A 90% confidence interval
for

Step-by-step explanation:

Information given

represent the sample mean

population mean (variable of interest)

s=4.15 represent the sample standard deviation

n=25 represent the sample size  

Confidence interval

The confidence interval for the mean is given by the following formula:

  (1)

The degrees of freedom, given by:

Since the Confidence is 0.90 or 90%, the significance is and , and the critical value is

Now we have everything in order to replace into formula (1):

b and c

step-by-step explanation: