The shelf life of a battery produced by one major company is known to be Normally distributed, with a mean life of 3.5 years and a standard deviation of 0.75 years. If a sample of size 20 is repeatedly chosen at random, what is the standard deviation $\sigma$_x of sample means? A) 3.5 years B) 0.75 years C) 0.17 years D) 0.04 years

Question

Quizplus · Accepted Answer

The standard deviation of sample means (also known as the standard error of the mean) is equal to the standard deviation of the population divided by the square root of the sample size. 
Thus, the standard error of the mean in this case would be:
0.75 / sqrt(20) = 0.1677 ≈ 0.17 years. Therefore, the answer is choice C.

The Shelf Life of a Battery Produced by One Major σ\sigmaσ

The Shelf Life of a Battery Produced by One Major $\sigma$