Question

on a certain sum of money,invested at the rate of 10 percent per annum compounded annually,the interest for the first year plus the interest for the third year is 2652.find the sum.

Answer 1

Let the sum be P
As , A = P(1 +R/100)^t
⇒A = P(1+10/100)
Interest = P/10
now, for 3rd year interest, the amount at the end of 2nd year will be sum.
i.e.
A = P(1 +10/100)^2
   =121P/100
now amount for 3rd year will be
A = (121P/100)(1 +10/100)
   =1331P/1000
interest = 331P/1000
A/q
P/10 + 331P/1000 = 2652
⇒431P/1000 = 2652
⇒P ≈ Rs 6153