Forever Power Company analysts conducted tests on the life of its batteries and those of a competitor (Brand X). They found that their batteries had a mean life (in hours) of 26.6, with a standard deviation of 4.3. Their results for a sample of 10 Brand X batteries were as follows: 13, 17, 20, 24, 26, 26, 29, 32, 34, 37.
a. Find the mean and standard deviation for the sample of Brand X batteries.
b. Which batteries have a more uniform life in hours?
c. Which batteries have the highest average life in hours?