posted by SHelia on .
The distribution of scores on a standardized aptitude test is approximately normal with a mean of 490 and a standard deviation of 95. What is the minimum score needed to be in the top 25% on this test? Carry your intermediate computations to at least four decimal places, and round your answer to the nearest integer.
Z = (score-mean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.25) in smaller portion to get the Z score. Insert values in the equation above.