Question

A sum of money lent at C.I. amounts to ₹1815 in two years and to ₹1996.50 in three years. Find the sum and rate %.​

Answer 1

Step-by-step explanation:

Between 2 and 3 years the money has increased to 1996.5/1815=1.1 which is an increase of 0.1 or 10%.

If P is the original sum then 1815=P(1.1)² and P=1815/1.21=₹1500.

Answer 2

Solution :-

→ Amount after 2 years = Rs.1815

→ Amount after 3 years = Rs.1996.5

So,

→ Amount increase from 2nd year to 3rd year is compound interest = 1996.5 - 1815 = Rs.181.5 .

Now, we can say that, we get Rs.181.5 as interest for 1 year on amount Rs.1815 .

Therefore,

→ Req. Rate = (181.5 * 100) / 1815 = 10% PA. (Ans.)

______________

Now, we have ,

→ Rate = 10% pa

→ Time = 2 years.

→ Amount = Rs.1815

→ Principal = Let P

So,

→ A = P[ 1 + (R/100)]^T

→ 1815 = P[ 1 + (10/100)]²

→ 1815 = P(11/10)²

→ 1815 = P(121/100)

→ P = (1815 * 100) / 121

→ P = Rs.1500 (Ans.)

Hence, Sum is Rs.1500 and Rate is 10% PA.