The life in hours of a battery is known to be approximately normally distributed, with standard deviation s = 1.25 hours. A random sample of 10 batteries has a mean life of x ¯=40.5 hours.
(a) Is there evidence to support the claim that battery life exceeds 40 hours? Use a = 0.05.
(b) What is the P-value for the test in part (a)?
(c) Calculate an appropriate con?dence interval on life and use to answer part (a)