Question 761498
Suppose a group of individuals in an area showed an average IQ of 105 with standard deviation of 10. If a sample of 100 individuals from the group is taken, what is the probability that the mean IQ of the individuals is between 102.5 and 106.75? 
--------
z(102.5) = (102.5-105)/[10/sqrt(100)] = -2.5
---
z(106.75) = (106.75-105)/[10/sqrt(100)] = 1.75
-----
P(102.5 < x-bar < 106.75) = P(-2.5 < z < 1.75) = 0.9537
==========================================================
Cheers,
Stan H.
=============