Question

A certain sum of money. amounts to
1344 in 3 years and 1440 in 5 years.
Find the sum and rate of interest. Pls tell ​

Answer 1

● Answer -

Rate of interest = 4 %

Sum of money = 1200 Rs

● Explanation -

Let P be sum of money and r be rate of interest.

After 3 years,

Total = 1344

P (1 + r×3) = 1344

P (1 + 3r) = 1344 ...(1)

After 5 years,

P (1 + r×5) = 1440

P (1 + 5r) = 1440 ...(2)

Dividing (1) by (2),

[P(1+3r)] / [P(1+5r)] = 1344 / 1440

(1+3r) / (1+5r) = 42 / 45

45 (1+3r) = 42 (1+5r)

45 + 135r = 42 + 210r

210r - 135r = 45 - 42

75r = 3

r = 3/75

r = 1/25

r = 1/25 × 100 %

r = 4 %

Principal would be -

P (1 + 5×4/100) = 1440

P (1 + 1/5) = 1440

P = 1440 × 5/6

P = 1200 Rs