Posted by tammy on Sunday, April 29, 2012 at 6:19pm.
For a normal distribution with a mean of 140 and a standard deviation of 55 find each value requested.
a. What is the minimum score needed to be in the bottom 10% of the distribution?
b. What scores form the boundaries for the middle 75% of the distribution.

statistics  PsyDAG, Monday, April 30, 2012 at 2:29pm
Z = (scoremean)/SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportion (.10) related to the Z score. Insert values to find score.
Middle 75% = ± .375 between score and mean. Use the same table.