Power+, produces AA batteries used in remote-controlled toy cars. The mean life of these batteries follows the normal probability distribution with a mean of 17 hours and a standard deviation of 4.6 hours. As a part of its testing program, power+ tests samples of 25 batteries. Use for the Z-values.

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

Shape of the distribution is

b. What is the standard error of the distribution of the sample mean?

Standard error

c. What proportion of the sample will have a mean useful life of more than 18 hours?

Probability

What proportion of the sample will have a useful life greater than 16.5 hours?

Probability

What proportion of the sample will have a mean useful life between 16.5 and 18 hours?

Probability