What will be the intelligence quotient of a 15 year old boy, when his mental age is 12 ?

Question

Accepted Answer

The intelligence quotient (IQ) is calculated using the formula:

IQ = (Mental Age / Chronological Age) * 100

In this case, the boy's mental age is 12 and his chronological age is 15.  Therefore:

IQ = (12 / 15) * 100
IQ = 0.8 * 100
IQ = 80

Therefore, Option 1 (80) is the correct answer.

Now, let's explain why the other options are incorrect:

*   **Option 2 (90):**  If the IQ were 90, then (Mental Age / 15) * 100 = 90.  Solving for Mental Age would give us 13.5, which contradicts the given information that the mental age is 12.

*   **Option 3 (100):** An IQ of 100 would mean the mental age equals the chronological age.  In this case, it would mean the mental age is 15, which contradicts the given information that the mental age is 12.

*   **Option 4 (110):** If the IQ were 110, then (Mental Age / 15) * 100 = 110. Solving for Mental Age would give us 16.5, which contradicts the given information that the mental age is 12.

Only Option 1, resulting in an IQ of 80, aligns with the given mental age of 12 and chronological age of 15 when using the standard IQ formula.