Question

What sum of money lent for 3 year and 4% per year will amount to rupees 392?

Answer 1

Given :

Total Amount : ₹392

Rate of interest : 4%

Time : 3 years

To find :

Principle amount lent to the person.

Solution :

First, we will find the simple interest.

Simple interest :

Let the principle amount be y.

$\sf \dashrightarrow SI = \dfrac{P \times R \times T}{100}$

$\sf \dashrightarrow \dfrac{y \times 4 \times 3}{100}$

$\sf \dashrightarrow \dfrac{y \times 12}{100}$

$\sf \dashrightarrow \dfrac{12y}{100}$

Now, we can find the value of the principle i.e, value of y by the formula of total amount.

Total Amount :

$\sf \dashrightarrow Simple \: Interest + Principle$

$\sf \dashrightarrow \dfrac{12y}{100} + y = 392$

$\sf \dashrightarrow \dfrac{12y + 100y}{100} = 392$

$\sf \dashrightarrow \dfrac{112y}{100} = 392$

$\sf \dashrightarrow 112y = 392 \times 100$

$\sf \dashrightarrow 112y = 39200$

$\sf \dashrightarrow y = \dfrac{39200}{112}$

$\sf \dashrightarrow y = 350$

Hence, the principle amount is ₹350.