maths
posted by boby .
Suppose scores on an IQ test are normally distributed.If the test has mean of 100 and standard deviation of 10,what is the probability that a person who takes the test will score between 90 and 110?

the following website is perfectly suited for your problem
http://davidmlane.com/hyperstat/z_table.html
enter:
mean: 100
SD: 10
click on between, and set at 90 and 110
I get .682689