Posted by Anonymous on Sunday, October 9, 2011 at 4:47pm.
For the overall population, the IQ scores follow the normal distribution with mean equal to 100 and variance equal to 225. What is the best answer?
A. If you pick a person at random, the chance that his IQ falls
between 100 to 115 is more than the chance that his IQ falls
between 6085.
B. If you pick a person at random, the chance that his IQ falls
between 100 to 115 is as compared to falling between 65 to 80
depends on the number of the outliers.
C. If you pick a person at random, the chance that his IQ falls
between 100 to 115 is not comparable to his IQ falling between
6085.
D. If you pick a person at random, the chance that his IQ falls
between 100 to 115 is less than the chance that his IQ falls
between 65 to 80.

Statistics  PsyDAG, Monday, October 10, 2011 at 2:04pm
Standard deviation = square root of variance = 15
Z = (scoremean)/ SD
Find table in the back of your statistics text labeled something like "areas under normal distribution" to find the proportions related to these Z scores.