# Linear Inequations-22

### From Homeworkwiki

**IQ of a person is given by the formula**

**IQ = MA/CA X 100,**

**where MA is the mental age and CA is the chronological age.**

**If 80 ≤ IQ ≤ 140 for a group of 12 year children, find the range of their mental age.**

**Solution:** We have, CA = 12 years.

Therefore, IQ = MA/CA X 100 => IQ = MA/12 X 100 = 25MA/3

Now, 80 ≤ IQ ≤ 140

=> 80 ≤ 25MA/3 ≤ 140

=> 240 ≤ 25MA ≤ 420

=> 240/25 ≤ MA ≤ 420/25

=> 9.6 ≤ MA ≤ 16.8