Probability and normal distribution

[ChrisHP]

Hoping this is out there somewhere, just can't find it.

How do I find the probability of a sample mean being a given distance from the population mean?

I.e. If the population has a mean of 70, and sd of 5, what is the probability that a sample of size 4 will have a mean of less than 65?

I can do it in many stages, but is there an app or function that will do it directly? It seems quite a common task to want to do.