Posted by Darren on Sunday, March 3, 2013 at 1:16pm.
Given that the general population is normally distributed on a standard scale measuring math aptitude with Mean = 50 (s.d. = 10), approximately what percentage of the population has a math aptitude score between 40 and 60?

statistics  Dr. Jane, Sunday, March 3, 2013 at 1:24pm
You need to find the zscore
(40  50)/10 = z
(60  50)/10 = z
So, you are looking for 1 and +1 standard deviations.
Find the area between 1 and +1 standard deviation by using a ztable or else by using the 65.. etc, rule. 
statistics  Anonymous, Saturday, February 27, 2016 at 1:11pm
68.2%