The modulus of rupture (MOR) for a specific grade of pencil lead is known to have standard deviation of 250 psi. Process standards call for a target value of 6500 psi for true mean MOR. For each batch, an inspector tests the random sample of 16 leads. Management desires to detect any change in true mean MOR.
a. A current random sample yielded the sample mean of 6490 psi. Conduct hypothesis test to find out whether the true mean MOR has changed from the target. Use a 0.10 significance level.