A sum amounts to Rs 9680 in 2 years and to Rs 10648 in 3 years respectively at compound interest Wha...........

Quantitative Aptitiude (CLAT) Compound Interest

A sum amounts to Rs. 9680 in 2 years and to Rs. 10648 in 3 years respectively at compound interest. What will be the amount if the same sum is invested for 1 2/5 years at the same rate of compound interest?

Rs.9050

Rs.9150

Rs.9215

Rs.9251

Explanation:

Amount = P[ (1+r)^n ]
9680 = P [ (1+r)^2 ] -(eq 1)
10648 = P [ (1+r)^3 ] -(eq 2)
On dividing eq 1 by eq 2 , we get
1210/1331 = 1/(1+r)
1210+1210r = 1331
r = 121/1210
r = 1/10. (means rate = 10%)
Putting value of r in any of the eqns ,we get
P = 8000
For , 1 2/5 yrs or 7/5 yrs -
A = 8000 [ (1+1/10) ^ (7/5) ]
A = 8000 [ (1.1) ^ (1.4) ]
A = 8000*1.14274
A = 9141.9
So , A = Rs. 9142 (approx.)