A sample of size n=10 is drawn from an approximately normal population whose standard deviation iso= 12.5. The sample mean is x = 50.9. Construct a 99% confidence interval for u.

a. 40.72 << 61.08
b. 48.02 < < 53.78
c. 50.90 < p < 61.08
d. 43.61 < p < 58.19