The Height (In Inches) of Males in the United States

The height (in inches) of males in the United States is believed to be Normally distributed. The average height of a random sample of 50 American adult males is x̄= 69.72 inches, and the standard deviation of the 50 heights is s = 4.23. What is the standard error of x̄?

A) 0.084
B) 0.357
C) 0.598
D) 0.731