Question

A man invest a part of 10,000 at 5% and the remainder at 6%. The 5% investment yields annually rs 76.50 more than the 6%

Answer 1

The simple interest for 2 years = Rs. 400

So, S. I. for 1 year = 400/2 = Rs. 200

Compound Interest for 1 years = Rs. 200

And C. I. for two years = Rs. 410

Therefore Compound interest for 2 years = C. I. for 1st year + C.I. for 2nd year

C. I. for 2nd year = Rs. 410 - Rs. 200 = Rs. 210

The difference = 210 - 200 = Rs. 10

So, after 1 year Amount = Rs. 210 and P = Rs.200

A = P(1 + r/100)¹ {This formula is used with Amount as Rs. 210 because the compound interest and simple interest for the 1st year are same.}

210 = 200(1 + r/100)¹

210/200 = 1 + r/100

1.05 = 1 + r/100

1.05 - 1 = r/100

0.05 = r/100

r = 100*0.05

r = 5 %