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.

1260

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