Question

Rohit invested $₨10,000$ at $18\%$ p.a. $3$ years later , he invested another $₨5,000$. What amount will he get $6$ years hence?

Answer 1

Step 1: Find the simple interest for first $3$ years.

Given:

Principal $=₨10,000$

Rate of Interest $=18\%$ p.a

Time$=3$years

We know that

Simple interest $=\frac{\mathrm{P}\times \mathrm{R}\times \mathrm{T}}{100}$

Then,

Simple interest $=\frac{10000\times 18\times 3}{100}$
$$\begin{gathered} =100\times 18\times 3 \\ =5400 \end{gathered}$$

Hence, the interest for first $3$ years is $₨5400$.

Step 2: Find the simple interest for later $3$ years.

Since, $3$ year later, he invested another $₨5,000$.

So, principal for after $3$ year $=10000+5000=15000$

Then,

Simple interest $=\frac{15000\times 18\times 3}{100}$
$$\begin{gathered} =150\times 18\times 3 \\ =8100 \end{gathered}$$

Hence, the interest for later $3$ years is $₨8100$.

Step 3: Find the total amount after $6$ years.

Amount for the first $3$ year $=10000+5400=15400$

Amount for the later $3$ year $=15000+8100=23100$

Thus, total amount $=15400+23100=38500$.

Hence, he will get $₨38,500$ after $3$ years.