<prompt> A male child of 15 years, with a mental age of 9 years has an IQ of:50607080  <response>: Intelligence quotient IQ, is obtained by dividing the subjects mental age as determined by the Binet-Simon scale by his chronological age up to the 14th year and multiplying the result by 100. IQ of this child is 915 100 60 Ref: Introduction to Psychology By J. Mahmud, Page 236. 