A set of test scores is normally distributed with a mean of 78 and a standard deviation of 4.5. Dwayne scored 87 on the test. What is his percentile score?
The question requires z-scores.
The formula is:
This is a bit easier to remember :)
Plug in the values:
Now you look up the probability that corresponds to the
The probability that corresponds to the
All you have to do now is multiply by