Martin is 20 years old, but he scored like an average 15-year-old on the Stanford-Binet intelligence test. Martin's IQ would be approximately ____.
A) 125
B) 100
C) 75
D) 50

Question

Quizplus · Accepted Answer

The Stanford-Binet intelligence test is normed by age, so Martin's score of an average 15-year-old indicates that he performed as well as most 15-year-olds on the test. Therefore, we can assume that his mental age is 15. To calculate Martin's IQ, we divide his mental age (15) by his chronological age (20) and multiply by 100. So Martin's IQ would be (15/20) x 100 = 75.

Martin Is 20 Years Old, but He Scored Like an Average