AFCAT Model Paper 10

Given:
A sum of money (P) doubles in 10 years
Formula Used:
Simple interest =

PTR

100

Amount = P + Interest
Where, P = Principle, R = Rate, T = Time period
Calculation:
According to the question
Amount after 10 years = 2P
So, Simple Interest = A - P
⇒ Simple interest = 2P - P = P
⇒P×R×

10

100

=P R = 10%
When time is 20 years
⇒ Simple interest =R×T×

P

100

⇒ Simple interest =10×20×

P

100

⇒ Simple interest = 2P
⇒ Amount = P + 2P = 3P
∴ The amount after 20 years would be 3P.