Question

Match the rate of interest for each of the Final amount when $1000 is invested for 1 year in a bank.

• A. 8%
• B. 5%
• C. 18%
• D. 25%

Answer 1

You know,
Simple interest (SI) $=\frac{P\times R\times T}{100}$
where,
Principal amount invested = P
Rate of interest provided = R
Time period = T

In first case,
Amount received at end of 1 year (A) = $\$1080$
∴ Interest amount:
= $A-P=\$1080-\$1000=\$80$

Now, find what percentage of $\$1000$ is $\$80$.
You can write this as:

Amount $\left(\$\right)$	Percentage $\left(\%\right)$
1000	100
80	?

= $\frac{100\times 80}{1000}$
= $8\%$

So, the rate of interest given by the bank will be $8\%$.

In second case,
Amount received at end of 1 year (A) = $\$1050$
∴ Interest amount:
= $A-P=\$1050-\$1000=\$50$

Now, find what percentage of $\$1000$ is $\$50$.
You can write this as:

Amount $\left(\$\right)$	Percentage $\left(\%\right)$
1000	100
50	?

= $\frac{100\times 50}{1000}$
= $5\%$

So, the rate of interest given by the bank will be $5\%$.

In third case,
Amount received at end of 1 year (A) = $\$1180$
∴ Interest amount:
= $A-P=\$1180-\$1000=\$180$

Now, find what percentage of $\$1000$ is $\$180$.
You can write this as:

Amount $\left(\$\right)$	Percentage $\left(\%\right)$
1000	100
180	?

= $\frac{100\times 180}{1000}$
= $18\%$

So, the rate of interest given by the bank will be $18\%$.

And, finally, in fourth case,
Amount received at end of 1 year (A) = $\$1250$
∴ Interest amount:
= $A-P=\$1250-\$1000=\$250$

Now, find what percentage of $\$1000$ is $\$250$.
You can write this as:

Amount $\left(\$\right)$	Percentage $\left(\%\right)$
1000	100
250	?

= $\frac{100\times 250}{1000}$
= $25\%$

So, the rate of interest given by the bank will be $25\%$.