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
The answer is B Sometimes
Answer:
x=0.875
Step-by-step explanation:
2×+y=1
y=0.5
4×+2y=-1
4×+2.5=-1
1+2.5=4x
3.5=4x
x=0.875
40,000 divided by 20 = 500
500 x 12 (which was 20-8)= 6,000
6,000 students