Question

sadhna deposits rupees 12000 in a bank and gets rupees 1200 as interest in 4 years. find the rate of interest at which money was lent ...​

Answer 1

Given :

Principle : ₹12000

Simple interest : ₹1200

Time : 4 years

To find :

The rate of interest at which money was lent.

Solution :

To find the rate of interest, we use the formula of simple interest.

Rate of interest :

$\sf \dashrightarrow Simple \: interest = \dfrac{P \times R \times T}{100}$

$\sf \dashrightarrow 1200 = \dfrac{12000 \times R \times 4}{100}$

$\sf \dashrightarrow 1200 = \dfrac{48000 \times R}{100}$

$\sf \dashrightarrow R = \dfrac{1200 \times 100}{48000}$

$\sf \dashrightarrow R = \dfrac{1 \times 100}{40}$

$\sf \dashrightarrow R = \dfrac{100}{40} = \dfrac{5}{2}$

$\sf \dashrightarrow R = 2.5\%$

Hence, the rate of interest at which money was lent is 2.5%.

$\:$

Verification

$\sf \dashrightarrow Simple \: Interest = \dfrac{P \times R \times T}{100}$

$\sf \dashrightarrow 1200 = \dfrac{12000 \times 5 \times 4}{100 \times 2}$

$\sf \dashrightarrow 1200 = \dfrac{12000 \times 20}{100 \times 2}$

$\sf \dashrightarrow 1200 = \dfrac{12000 \times 10}{100 \times 1}$

$\sf \dashrightarrow 1200 = \dfrac{120000}{100}$

$\sf \dashrightarrow 1200 = 1200$

$\sf \dashrightarrow LHS = RHS$