LongLast Inc. produces car batteries. The mean life of these batteries is 60 months. The distribution of the battery life closely follows the normal probability distribution with a standard deviation of 8 months.

Question

LongLast Inc. produces car batteries.  The mean life of these batteries is 60 months.  The distribution of the battery life closely follows the normal probability distribution with a standard deviation of 8 months.

As part of its testing program, LongLast tests a sample of 25 batteries.

What is the standard error of the mean?

Damon · Answer

try: http://davidmlane.com/hyperstat/z_table.html

Mark · Answer

That does not help calculate the standard of error.

Damon · Answer

http://www.miniwebtool.com/standard-error-calculator/ 8/sqrt(25) = 8/5 = 1.6