Power+,Inc. produces AA batteries used in remote controlled toy cars. The mean life of these batteries follows the normal probability distribution with a mean of 37 hours and a standard deviation of 5.5 hours. As part of its quality assurance program, Power+, Inc. tests samples of 9 batteries
a) What can you say about the shape of the distribution of the sample mean?
b) what is the standard error of the distribution of the sample mean? (Round your answer to 4 decimal place