Question

Rachit borrowed 15,000from his friend. He gave 3,000 at the rate of 15% per annum and the remaining amount at the rate of 18% per annum.
How much interest did he pay in 4 years?

with solution ​

Answer 1

Answer:

Let’s consider it to be simple interest.

Now, breaking down the question, Rs. 3000 was borrowed at a rate of 15% and Rs. 12000 (15000–3000) was borrowed at a rate of 18% p.a.

So, interest earned in 4 years on the sum of 3000 = (3000*15*4)/100 = Rs. 1800.

and interest earned in 4 years on the sum of 12000 = (12000*18*4)100 = Rs. 8640.

Therefore total interest payed in 4 years is (1800+8640) = Rs. 10440.

Answer 2

Given,

Total money borrowed $\[ = 15000\]$

Money at $\[15\% \]$ interest $\[ = 3000\]$

Remaining money at $\[18\% \]$ interest rate.

Time = 4 years

Solution,

Consider the amount is p, rate is r, and time is t, then interest,

$\[ = \frac{{p \times r \times t}}{{100}}\]$

Calculate the interest.

$\[ = \frac{{3000 \times 15 \times 4}}{{100}} + \frac{{\left( {15000 - 3000} \right) \times 18 \times 4}}{{100}}\]$

$\[ = \frac{{3000 \times 15 \times 4}}{{100}} + \frac{{12000 \times 18 \times 4}}{{100}}\]$

$\[ = 30 \times 15 \times 4 + 120 \times 18 \times 4\]$

$\[\begin{array}{l} = 1800 + 8640\\ = 10440\end{array}\]$

Hence the interest in 4 years is $\[10440\]$