IQ of a person is given by the formula
,
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.
Chronical age = CA = 12 years
IQ for age group of 12 is 80 ≤ IQ ≤ 140.
Let MA denote Mental Age
80 ≤ IQ ≤ 140
Putting 
⇒ 9.6 ≤ MA ≤ 16.8
∴ Range of mental age of the group of 12 years old children is
9.6 ≤ MA ≤ 16.8
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