Solution:

Test the hypothesis that the mean life of updated batteries type B is significantly longer than the regular batteries type A. Assume that population standard deviations are equal but unknown. (Hint: use pooled estimate of the standard deviation). Perform the Test at the a = 0.01 level using the following data. Population in hours Sample mean Sample standard Sample Size deviation X s IN Batteries type B 49.2 7.31 Batteries type A 41.1 6.40