Question

Your boss tells you that she knows the length of the widgets your company makes is normally distributed with a mean of 25 inches and a population standard deviation of 12 inches. If you take samples of size 9 from finished widgets in the warehouse, in order to check for quality, what will be the mean and standard deviation of the sampling distribution?

Answer 1

Answer:

Mean of sampling distribution = 25 inches

Standard deviation of sampling distribution = 4 inches

Step-by-step explanation:

We are given the following information in the question:

Mean, μ = 25 inches

Standard Deviation, σ = 12 inches

Sample size, n = 9

We are given that the distribution of length of the widgets is a bell shaped distribution that is a normal distribution.

a) Mean of the sampling distribution

The best approximator for the mean of the sampling distribution is the population mean itself.

Thus, we can write:

$\bar{x} = \mu = 25\text{ inches}$

b) Standard deviation of the sampling distribution

$s = \dfrac{\sigma}{\sqrt{n}} = \dfrac{12}{\sqrt{9}} = 4\text{ inches}$