A school counsellor in Pune is checking the record cards of students who took an age-graded intelligence test last month. One card reads: 'Tanvi, age 12 years; IQ 90.' The line on the card that shows the age level at which Tanvi actually performed on the test has been smudged by water and cannot be read. The counsellor wants to fill it in before the parents' meeting, using only the two figures that are still clear on the card.
Which mental age should the counsellor enter on Tanvi's card?
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → 10.8 years
Option (1) 13.3 years — Incorrect. This turns the ratio upside down (12 x 100 / 90). A mental age above 12 would give an IQ above 100, which does not match her IQ of 90.
Option (2) 10.8 years — Correct. IQ = MA / CA x 100, so MA = IQ x CA / 100 = 90 x 12 / 100 = 10.8 years. An IQ below 100 means the mental age is below the chronological age, and 10.8 is below 12.
Option (3) 11 years — Incorrect. This takes every 10 IQ points as one year of mental age. IQ is a ratio: an IQ of 90 means MA is 90 per cent of CA, which is 1.2 years below 12.
Option (4) 7.5 years — Incorrect. This divides the IQ by the age (90 / 12). That step is not part of the IQ formula, and the figure it gives is not Tanvi's mental age.
NCERT (2026-27): “Assessment of Intelligence … “The number 100 is used as a multiplier to avoid the decimal point. When the MA equals the CA, the IQ equals 100. If MA is more than the CA, IQ is more than 100. IQ becomes less than 100 when the MA is less than the CA. …” |