Question

mr. chopra deposited his savings in a bank deposit scheme. at the end of the third year his savings had grown to €6,41,250 and at the end of the fifth year to 7,21,406.25. how much money had mr. chopra deposited and at what percent interest?​

Answer 1

Answer:

Step-by-step explanation:

Given  

mr. chopra deposited his savings in a bank deposit scheme. at the end of the third year his savings had grown to €6,41,250 and at the end of the fifth year to 7,21,406.25. how much money had mr. chopra deposited and at what percent interest?

Let the initial amount be a and rate of interest be r

We know that SI = PRT / 100

Amount = P + SI

            = a + ar x 3 / 100

641250 = 100 a + 3 r a / 100

100 a + 3 r a = 64125000 ---------------1

Now after 5 years amount will be 721406.25

So 100 a + 5 r a = 72140625 -----------------2

From 1 and 2 we get

2 r a = 72140625 – 64125000

2 r a = 8015625

Now r a = 8015625 / 2

So r a = 4007812.5 -----------3

Substituting the value of r a in equation 2 we get

100 a + 5 x 4007812.5 = 72140625

100 a = 72140625 – 20039062.5

100 a = 52101562.5

a = 521015.625

So initial amount will be 521015.625

In eq’n 3 substitute the value of a we get

r a = 4007812.5

r (521015.625) = 4007812.5

r = 4007812.5 / 521015.625

r = 7.692%

So initial amount is Rs 521015.625 and rate of interest is 7.692%