Question

A sum of money at compound interest amounts to rs 3920 in one year and rs 4390.4 in2 years .Find the principal

Answer 1

Answer:

Principal is 3500/-

Step-by-step explanation:

let the principal be 'P'

Amount for 1st yr(A1) is rs 3920

Amount for 2nd yr(A2) is rs 4390.4

rate of interest(R)=(A2-A1)/A1

R=(4390.4-3920)/(3920)

R=(470.4)/(3920)

R=0.12

to get in %,R=0.12×100=12%

Now Principal is P

rate of interest is 12%

Amount at end of 1yr is 3920

12%

P------->0.12P is CI for 1st yr

To get amount add Principal to CI

Amount=P+0.12P

Amount=1.12P

but we know amount is 3920

1.12P=3920

P=3500/-