statistics
posted by Josh .
The diameter of small Nerf balls manufactured at a factory in China is expected to be approximately normally distributed with a mean of 5.2 inches and a standard deviation of .08 inch. Suppose a random sample of 20 balls is selected. Find the interval that contains 87% of the sample means.

87% = mean ± 1.51 SEm
SEm = SD/√n 
What is square root n?

The diameter of small Nerf balls manufactured at a factory in China is expected to be approximately normally distributed with a mean of 5.2 inches and a standard deviation of .08 inch. Suppose a random sample of 20 balls is selected. Find the interval that contains 87% of the sample means