I got halfway through this problem but am stumped on D and E.

The amount of active ingredient in a certain type of cold remedy tablet has mean 400.0 milligrams and standard deviation 4.5 milligrams. If a sample of 72 tablets is randomly selected, what is the probability that the mean amount of active ingredients in this sample is more than 401 milligrams?

A) Let x denote the amount of active ingredient in the cold remedy tablets. What’s known about the shape of the distribution of X?

It is a bell curve

B) Let X denote the mean amount of active ingredient in a sample of 72 of these cold remedy tablets. What is known about the shape of X-bar and why?

i. It is a normal distribution because the sample size, n, is greater than 30.

C) What is the mean of X-bar?

Mean of x-bar equals 400.0 because M of x-bar equals the M of x

D) What is the standard deviation of X-bar?

E) Solve the problem