Question

The I . Q . of students of a school was found to be normally distributed with a mean µ = 116 and a standard deviation of σ = 8 . What % age of children have I . Q . fr om 100 to 124 .

Answer 1

We use a z-statistic. z-value for 100 is (100-116)/8=-2. Using z-table we get that 22.8% of children have IQ lower than 100;
z-value for 124 is (124-116)/8=1. Using z-table we get that 84.13% of children have IQ lower than 124;

So, the percent of children with IQ between 100 and 124 is 55.33%