Chapter 30, Problem 5TYS

Summary Introduction

Concept Introduction: Intelligent quotient (IQ) was derived by German psychologist William Stern. IQ is used as a method to assess intelligence. IQ is the ratio of a person’s mental age to a person’s chronological age and multiplied by 100.

Answer to Problem 5TYS

Correct answer:  The IQ of a 6-year-old with the measured mental age of 9 would be 150. Therefore, option d. is correct

Explanation of Solution

Reasons for the correct statement:

The formula for IQ is as follows:

$\frac{\text{mental}\text{age}}{\text{chronological}\text{age}}\text{×100}$

The given information:

Mental age = 9 years

Chronological age = 6 years

$\begin{array}{c}\text{IQ=}\frac{\text{9}}{\text{6}}\text{×100}\\ \text{=}\frac{\text{900}}{\text{6}}\\ =150\end{array}$

Option d. is given as “150”

As IQ of a 6-year-old with the measured mental age of 9 would be 150, option d. is correct.

Reasons for the incorrect statements:

Option a. is given as “67”.

IQ of a 6-year-old with the measured mental age of 9 would be 150, not 67. So, option a. is incorrect.

Option b. is given as “133”.

IQ of a 6-year-old with the measured mental age of 9 would be 150, not 133. So, option b. is incorrect.

Option c. is given as “86”.

IQ of a 6-year-old with the measured mental age of 9 would be 150, not 86. So, option c. is incorrect.

Hence, options a., b., and c. are incorrect.

Conclusion

IQ is used as a method to assess the intelligence of an individual.