<prompt> A male child of 15 years with a mental age of 12 years has an IQ of -50607080  <response>: IQ mental agechronological age 100 mental age is 12 yr, chronological age is 15 yr so 1215 0.8, 0.8100 80 ref; page no;637 25th edition of PARKs textbook of Preventive and Social medicine 