Question

A certain sum under compound interest, interest being compounded annually earns an interest of rs. 864 and rs. 1,036.80 respectively in the third year and fourth year. Find the sum.

Answer 1

Answer:

Difference between when compounded at 6th year and 5th year= Rs. 6050 - Rs. 5500 = Rs.550

Time (6 years- 5 years)= 1 year

*We can calculate this as simple interest since time is one year. Thus,

Let rate be R

S.I. = PRT/100

550= 5500 x R x 1/100

550= 55R

550/55= R

10% = R

We can check:

Rs. 5500 x 10 x 1/100 = Rs. 550

Therefore S.I becomes Rs.550

Principal for next year is Rs. 6050.

Hence proved :)

Answer 2

Answer:

1036.8-864= 172.8

r= (172.8/864)×100 =20%

X×1/5 × 6/5×6/5=864 (1st year ci =1/5)

X=3000