An amount of Rs. ‘y’ was invested on (R-2)% per annum on simple interest and at the end of 6 years an amount of Rs. 23100 was obtained as an interest.
y x (R-2)% x 6 = 23100
y x (R-2) = 385000
y = 385000/(R-2) Eq.(i)
If the amount was Rs. 7000 more and the rate of interest was ‘R’% per annum on simple interest, then at the end of 4 years an amount of Rs. 22320 was obtained as an interest.
(y+7000) x R% x 4 = 22320
(y+7000) x R = 558000 Eq.(ii)
Put Eq.(i) in Eq.(ii).
[{385000/(R-2)}+7000] x R = 558000
After solving the above equation, R = 9 .
Put the value of ‘R’ in Eq.(i).
y = 385000/(9-2)
= 385000/7
y = 55000
Required compound interest = (y-5000) of (100+R+1)% of (100+R+1)% - (y-5000)
Put the values of ‘y’ and ‘R in the above equation.
= (55000-5000) of (100+9+1)% of (100+9+1)% - (55000-5000)
= 50000 of 110% of 110% - 50000
= 60500 - 50000
= Rs. 10500
