Posted by Susan on Saturday, March 10, 2012 at 3:21pm.
1. A test has a mean of 50, standard deviation of 10.
A. What scores separate the middle 25% from the rest
b. What proportion would be expected to score between 45 and 55
c. What proportion would be expected to score 68 and above

statistics  PsyDAG, Sunday, March 11, 2012 at 12:01pm
Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions and their related Z scores.
A. Find the Z score with .125 between score and mean. Insert ±Z value in the above equation and solve for the scores.
B and C. Solve for Z scores and use the table.