Question

A sum of money at simple interest amount to rs 696 in 2 years and rs 840in 5year . The sum

Answer 1

let sum be x
& interest rate be y
then
x(1+2y/100)=696.
or x=69600/(100+2y)
x(1+5y/100)=840
or x=84000/(100+5y).......(1)
putting the value of x in (1)
69600/(100+2y)=84000/(100+5y)
or 696(100+5y)=840(100+2y)
or 69600+3480y=84000+1680y
or 1800y=14400
or y=8
putting the value of y in (1)
x=84000/(100+5*8)
or x=84000/140
=600..........(ans)