Question

A certain sum of money at simple interest amounts to rs. 1260 in 2years and to rs. 1350 in 5 years. the rate percent per annum is

Answer 1

Let the Principal be P
In 3 years (As shown) , the interest increases the amount by Rs.90
So, interest per year = Rs. 30
So, interest for 5 years = Rs. 150
So, Principal = Rs.1350-Rs.150 = Rs. 1200

As, SI = PRT/100
So,     30 = 1200*R/100
  Simplifying,
30 = 12R
So, R = 30/12
          = 5/2 = 2.5%

Answer: The rate of interest is 2.5% p.a

Answer 2

Answer:

2.5% per annum

Step-by-step explanation:

S.I for 3 years = Rs. (1350 - 1260) = Rs. 90

S.I for 2 years = Rs.(90/3) x 2 = Rs . 60

∴ Sum = Rs. (1260 - 60) = Rs. 1200

∴ Rate = (100 x SI) / (P x T) = (100 x 60) / (1200 x 2) = 2.5%