Question

For a random sample of 10 men, the mean head circumference is x = 57.3 cm and the sample standard deviation is s = 2 cm. The standard error of the sample mean is:

a. 0.200
b. 0.447
c. 0.500
d. 0.632

Answer 1

2/sqrt(10) = 0.632

It is explained here:

http://en.wikipedia.org/wiki/Standard_error_(statistics)