The simple interest accrued on a certain principal is Rs. 1200 in 3 years at the rate of 8% per annum. What would be the compound interest (compounding annually) accrued on twice of that principal at the rate of 10% per annum in 2 years ?

Rs. 2,100

Principal(P)=?

Time(T)= 3 years

Rate  = 8 %

Simple Interest (S.I.) = 1200

If P=100

I=R×T

I=8×3

I=24%

ATQ

24%=1200

1%=50

100%=5000 Rs

If principal is twice i.e. 5000×2= Rs 10000

R=10%

T=2 years

Compound Interest for 2 years = R+R+\(\frac{R×R}{100}\)

= 10+10+\(\frac{10×10}{100}\)

= 21%

Interest = 21% of Principal

= \(\frac{21}{100}\)×10000

=2100 Rs