Question

on a certain sum ,the compound interest in 2years amounts to 4240.if the rates of interest for successive years are 10% and 15% respectively,find the sum.

Answer 1

Given

Time=2yr

Amount =4240

Successive rate of interest =10% and 15%

Let

Sum=100

Interest collected in 1 yr = pxrxt /100

Here r=10% y=1 p=100

Interest (1st yr) = 100x10x1/100

=10

Amount after 1 yr=sum+ interest =100+10

=110

Now 110 is sum for 2nd yr

Interest =pxrxt/100

Here=> p=110, r=15, t=1

Interest =110x15x1/100

=16.5

Amount after 2nd yr=110+16.5

=126.5

But according to the question amount after 2nd yr =4240

1 unit assumed =4240/126.5

=31.5177

Sum=100x31.5177

=₹3151.77

Approx =₹3152

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