Question

The difference between



c.i and s.i of rs. 2500 for 2 years is rs 400. so find the rate %?

Answer 1

Simple interest factor :

Principle × time × rate

2500 × 2 × r = 5000r

5000r

Compound interest accumulation factor :

(1 + r)^2 × 2500

Interest :

(1 + r) ^2 2500 - 2500

(1 + r) ^2 × 2500 - 2500 - 5000r = 400

(1 + r) ^2 × 2500 - 5000r = 2900

Divide through by 2500:

(1 + r)^2 - 2r = 1.19

1 + r - 1.4142r^0.5 = 1.09087

Log r - 0.5 × 1.4142 log r = log 1.09087

Log r (1 - 0.7071) = 0.037773

Log r = 0.037773/0.2929

Log r = 0.12896

r = Anti - log 0.12896

r = 1.3457

r = 1.3457