Rs. 12600 is invested in three parts in such a way that the simple interest on 1st part at 2% per annum for 3 years, on 2nd part at 3% per annum for 4 years and on 3rd part at 4% per annum for 5 years are equal. Find total interest received from all parts.
Answer & explanation
Correct answer: option 3
Let the principal P divides in three parts i.e P1,P2 and P3
ATQ,
P₁ x 2% x 3 = P₂ x 3% x 4 = P₃ x 4% x 5
P₁ x 6 = P₂ x 12 = P₃ x 20
P₁ x 3 = P₂ x 6 = P₃ x 10
P₁ : P₂ : P₃ = \(\frac{1}{3}\) : \(\frac{1}{6}\) : \(\frac{1}{10}\) = \(\frac{10\;:\;5\;:\;3}{30}\) = 10 : 5 : 3
(Total) 18R = 12600
⇒ 1R = 700
⇒ P1 = 10R = 10 x 700 = 7000
⇒ S.I on P1 = 7000 x 2% x 3 = 420
ATQ, S.I. on each part is same, therfore,
Total S.I. = S.I on P1 x 3 = 420 x 3 = 1260