Rachna borrowed a certain sum at the rate of 15% per annum. If she pai

1.	Rachna borrowed a certain sum at the rate of 15% per annum. If she paid at the end of two years Rs. 1290 as interest compounded annually, find the sum she borrowed.
Answer» Given, Rate = 15% p.a Time = 2 years C.I = Rs. 1290 Let principal = P So, Compound interest \(={P}[({1}+\frac{R}{100})^T-{1}]\) \(={P}[({1}+\frac{15}{100})^2-{1}]\) = 1290 \(={P}[(\frac{23}{20})^2-{1}]\) = 1290 \(={P}\times\frac{129}{400}\) = 1290 \(={P}=\frac{1290\times400}{129}\) = Rs. 4000 Hence, Principal = Rs. 4000

Rachna borrowed a certain sum at the rate of 15% per annum. If she paid at the end of two years Rs. 1290 as interest compounded annually, find the sum she borrowed.

Answer»

Given,

Rate = 15% p.a

Time = 2 years

C.I = Rs. 1290

Let principal = P

So,

Compound interest \(={P}[({1}+\frac{R}{100})^T-{1}]\)

\(={P}[({1}+\frac{15}{100})^2-{1}]\) = 1290

\(={P}[(\frac{23}{20})^2-{1}]\) = 1290

\(={P}\times\frac{129}{400}\) = 1290

\(={P}=\frac{1290\times400}{129}\) = Rs. 4000

Hence,

Principal = Rs. 4000