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?
try:
http://davidmlane.com/hyperstat/z_table.html
That does not help calculate the standard of error.
http://www.miniwebtool.com/standard-error-calculator/
8/sqrt(25) = 8/5 = 1.6
To calculate the standard error of the mean, you need to divide the standard deviation by the square root of the sample size.
In this case, the standard deviation of the battery life is given as 8 months, and the sample size is 25.
Using the formula, the standard error of the mean (SE) can be calculated as:
SE = standard deviation / √(sample size)
SE = 8 / √(25)
SE = 8 / 5
SE = 1.6 months
Therefore, the standard error of the mean for the sample of 25 batteries is 1.6 months.