Which of the following statement correctly describes the normal distribution of IQ scores?
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → IQ scores are symmetrically distributed around the mean, forming a bell-shaped curve
Option (1) Most people have extremely high or low IQ scores — Incorrect. It is the other way round: the scores of most people fall in the middle range, and only a few people have very high or very low scores.
Option (2) IQ scores are randomly distributed without a pattern — Incorrect. The distribution has a definite pattern: many scores near the average of 100 and fewer and fewer towards both ends.
Option (3) IQ scores are symmetrically distributed around the mean, forming a bell-shaped curve — Correct. The frequency distribution of IQ scores tends to approximate a bell-shaped curve, called the normal curve, which is symmetrical around the central value, the mean (100). About half the population lies between 90 and 109.
Option (4) All people have the same IQ — Incorrect. People differ in intellectual capacity: some are exceptionally bright and some below average, which is why a distribution exists at all.
NCERT (2025-26): “Assessment of Intelligence … IQ scor es ar e distributed in the population in such a way that the scores of most people tend to fall in the middle range of the distribution. Only a few people have either very high or very low scores. The frequency distribution for the IQ scores tends to approximate a bellshaped curve, called the normal curve. This type of distribution is symmetrical around the central value, called the mean.…” |