A random sample of size 36 is to be taken from a population that is normally distributed with mean 72 and standard deviation 6. The sample mean of the observations in our sample is to be computed. The sampling distribution of the sample mean is

Select one:

a.normal with mean 72 and standard deviation 6.

b.normal with mean 12 and standard deviation 6.

c.normal with mean 72 and standard deviation 1.

d.normal with mean 36 and standard deviation 18.