AFCAT I 2011 Solved Paper

In case of Simple interest, total amount A is,
A=P(1+‌

rt

100

)
where
P= Principal ( given 10000)
r= interest rate
t= time (in years) =15 (given)
After 15 years, Sum of money doubles itself, that is A=20000
Now apply the formula,
20000=10000(1+‌

r15

100

)
20000=10000(1+‌

15r

100

)
2=1+‌

15r

100

1=‌

15r

100

Therefore,
r=‌

100

15

=6.67%