Question

the difference between compound interest & simple interest at the same rate for rs 5000 for 2 years is RS 72 . find the rate of interest​

Answer 1

Step-by-step explanation:

Let the rate per cent p.a.be r. Then,

S.I.=Rs.(5000×100r×2)=Rs.100r

C.I.=Rs.⎣⎢⎡5000(1+100r)2−5000⎦⎥⎤

=Rs.5000⎣⎢⎡(1+100r)2−1⎦⎥⎤

=Rs.5000[(1+10000r2+1002r)−1]

=Rs.5000(10000r2+50r)=Rs.100005000(r2+200r)

∴C.I.−S.I.=72

⇒2r2+100r−100r=72

⇒2r2=72 

⇒r2=144

⇒r=12%p.a.