AFCAT Model Paper 3

Given:
Amount = 9 × Principal, Time 32 years
Formula Used:
Let P = principal, N = time and R = rate percent per annum
Then,
Simple interest =

(P×N×R)

100

Calculation:
According to the question
Amount = S.I + Principle
9P=(

(P×32×R)

100

)+P
⇒ 900P = 32PR + 100P
⇒ 800 = 32R
⇒ R =

800

32

⇒ R = 25%
Now, Again according to the question
19P=(

(P×N×25)

100

)+P
⇒19P=

NP

4

+P
⇒19=

N

4

+1
⇒ 76 = N + 4
⇒ N = 76 - 4
⇒ N = 72
∴ In 72 years, amount will becomes 19 times its principle.