A random sample of n = 8 E-glass fiber test specimens of a certain type yielded a sample mean interfacial shear yield stress of 32.9 and a sample standard deviation of 4.9. Assuming that interfacial shear yield stress is normally distributed, compute a 95% CI for true average stress. (Give answer accurate to 2 decimal places.)

Step-by-step explanation:

Information given

represent the sample mean for the sample  

population mean (variable of interest)

s=4.9 represent the sample standard deviation

n=8 represent the sample size  

Confidence interval

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

  (1)

the degrees of freedom are given by:

Since the Confidence is 0.95 or 95%, the value of and , and the critical value for this cae would be

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

0.02040816326