Power +, Inc. produces AA batteries used in remote-controlled toy cars. The mean life of these batteries follows a normal distribution with a mean of 38 hours and a standard deviation of 5.9 hours. As a part of its quality assurance program, Power +, Inc. tests samples of 16 batteries.

a.	What can you say about the shape of the distribution of the sample mean?

Sample mean

(Click to select) Normal Uniform Binomial

Round answers to four decimal places.

b.	What is the standard error of the distribution of the sample mean? Note: The standard error is the standard deviation of the distribution of the sample mean. That is, the standard error is the population standard deviation divided by the square root of the sample size.

Standard error

c.	What proportion of the samples will have a mean useful life of more than 39 hours?

Probability

d.	What is the probability that a randomly selected AA battery will have a useful life of at most 36.5 hours?

Probability

e.	What proportion of the samples will have a mean useful life between 36.5 and 39 hours?

Probability