Question

If rate of compound interest in 1st year 2nd year and 3rd year is 10%, 20% and 30% PA. respectively. Interest earned on 2nd year is Rs 13200. Then find the interest earned on 3rd year

Answer 1

to simplify this let principle be 100 rs

then interest after first year with 10% rate is 10 rs


for second year principle being 100 +10 = 110 rs

now interest for second year with 20% rate be

22 rs

but actually it is 13200 rs


if 110 ------- 22
then ?? ------ 13200

= 13200 × 110 / 22

= 66000

which is principle of the second year

therefore principle for third year

= 66000 + 13200 = 79200

interest for third year = 79200 × 30 /100

= 23760 rs