# Thread: Can't remember how to calculate this: P(X< = 54) with mean 63.5 and s.dev. 12.2;

1. ## Can't remember how to calculate this: P(X< = 54) with mean 63.5 and s.dev. 12.2;

assume distributed
assume distributed normally.

2. Just use $z=\frac{x-{\mu}}{\sigma}$

3. the answer i obtain from that is my final answer, correct?

4. You will have to look up the probability in the z-table which corresponds to the z-score you find from the formula.