# Probability, when i know the mean and std. dev

#### billovfo

##### New Member
Hi. I have a normal distribution, where the mean is 900.000 and the standard deviation is 150.000.
The first question is, i need to find the probability that the value is under 500.000 in a given summer month, and i've got the result 0,38% with the help of a statistical software named JMP.

The second question is i need to find the standard deviation, when the probability is 5%. I don't really know how to find the solution

#### Con-Tester

##### Member
The answer to the first question you gave is correct: P(x < 500.000) = 0,38%.