A sum of money at simple interest amounts to Rs. 400 in 4 years and to Rs. 450 in 9 years. Find the rate of interest per annum.
Answer & explanation
Correct answer: option 1
P + SI of 4 years = 400 (1)
P + SI of 9 years = 450 (2)
(1) - (2)
SI of 5 years = 50
SI of 4 years = 40
Principal ⇒ 400- 40 = 360
Rate = \(\frac{40 × 100}{360 × 4}\) = 2.77%