Question

IQ of a person is given by the formula $IQ = \frac{MA}{CA}×100,$ Where MA is mental age and CA is chronological age. If 80 ≤ IQ ≤ 140 for a group of 12 years old children, find the range of their mental age.

Answer 1

It is given that for a group of 12 years old children,
80 ≤ IQ ≤ 140 .…. (i)
For a group of 12 years old children, CA = 12 years
$\frac{MA}{12}×100$
Putting this value of IQ in (i), we obtain
$80 ≤ \frac{MA}{12} x 100 ≤ 140$
$⇒ 80 x \frac{12}{100} ≤ MA ≤ 140×\frac{12}{100}$
⇒ 9.6 ≤ MA ≤ 16.8
Thus, the range of mental age of the group of 12 years old children is 9.6 ≤ MA ≤ 16.8