Question

A sum of money amounts to
RS 7475 in 3 years and Rs 7800
in 4 years at the same rate
of simple intrest. The rate of
intrest is​

Answer 1

15 %

It is simple interest.

P + 4I = 2400 where p is principle and I is yearly interest. Remember, it is simple interest, so the interest is calculated only on the principal every year and is a constant over 4 years

P+4 (I*1.2) = P+ 4.8I =25800.

Subtraction of both the equations leads to

0.8I =1800

I = 2250

P = 15000 by solving (P+ 2250*4= 24000)

Rate of interest is 2250/15000 =15%