Question

(PLEASE HELP ASAP!!). One's intelligence quotient, or IQ, varies directly as a person's mental age and inversely as that person's chronological age. A person with a mental age of 15 and a
chronological age of 30 has an IQ of 120: What is the chronological age of a person with a mental age of 20 and an IQ of 120?
The chronological age is

Answer 1

Answer:40

Step-by-step explanation:This is a variation question

From the statement. Let the mental age be M and the chronological  age be C, then

IQ ∝M ∝1/C

⇒ IQ ∝ M/C

Introducing the proportionality constant

IQ = KM/ C

Given : M = 15, C = 30 , 1Q = 20

Substitute the given values into the equation

i.e 120 = K x 15/ 30

    120 = k/2

therefore k = 240

substitute k = 240 into the equation, we have

IQ = 240M/C

To find C when IQ is 120 and M is 20, we will substitute into the generated formula

i.e 120 = 240 x 20 / c

     120c = 480

            C = 480/120

             C = 40

Therefore , the chronological age of a person with mental age of 20 and IQ of 120 is 40