# Interest aptitude mcq

## Click on any option to know the CORRECT ANSWERS

 Question 1
Rs. 2100 is lent at compound interest of 5% per annum for 2 years. Find the amount after two years.
 A Rs. 2320 B Rs. 2315.25 C Rs. 2300 D Rs. 2310

Question 1 Explanation:
\begin{align} & {\text{We}}\, {\text{can}}\, {\text{use}}\, {\text{formula}}\, {\text{of}}\, {\text{compound}}\, {\text{interest}} \cr & A = P \times {\left[ {1 + \left( {\frac{r}{{100}}} \right)} \right]^n} \cr & A = 2100 \times {\left[ {1 + \left( {\frac{5}{{100}}} \right)} \right]^2} \cr & A = 2100 \times {\left[ {\frac{{105}}{{100}}} \right]^2} \cr & A = \frac{{\left( {2100 \times 11025} \right)}}{{10000}} \cr & {\text{Hence, }}\, {\text{Amount}}\, A = Rs.\, 2315.25 \cr\end{align}
 Question 2
If the rate increases by 2%, the simple interest received on a sum of money increases by Rs. 108. If the time period is increased by 2 years, the simple interest on the same sum increases by Rs. 180. The sum is:
 A Rs. 1800 B Rs. 5400 C Rs. 3600 D Data inadequate

Question 2 Explanation:
\begin{align} & {\text{Let the sum be Rs}}{\text{. }}x \cr & {\text{Rate be R}}\% {\text{ p}}{\text{.a}}{\text{.}} \cr & {\text{Time be T years}}{\text{.}} \cr & {\text{Then, }} \cr & \left[ {\frac{{x \times \left( {{\text{R}} \times 2} \right) \times {\text{T}}}}{{100}}} \right] - \left( {\frac{{x \times {\text{R}} \times {\text{T}}}}{{100}}} \right) = 108 \cr & \Leftrightarrow 2x{\text{T}} = 10800\, .....(i) \cr & And, \cr & \left[ {\frac{{x \times {\text{R}} \times \left( {{\text{T}} + 2} \right)}}{{100}}} \right] - \left( {\frac{{x \times {\text{R}} \times {\text{T}}}}{{100}}} \right) = 108 \cr & \Leftrightarrow 2x{\text{R}} = 18000\, .....(ii) \cr\end{align} Clearly, from (i) and (ii), we cannot the find the value of x.

 Question 3
A sum of Rs. 725 is lent in the beginning of a year at a certain rate of interest. After 8 months, a sum of Rs. 362.50 more is lent but at the rate twice the former. At the end of the year, Rs. 33.50 is earned as interest from both the loans. What was the original rate of interest?
 A None of these B 5% C 3.60% D 4.50%

Question 3 Explanation:
Let the original rate be R%. Then, new rate = (2R)%.

Note:

Here, original rate is for 1 year(s); the new rate is for only 4 months i.e. 1/3 year(s).

\begin{align} & \therefore \left( {\frac{{725 \times R \times 1}}{{100}}} \right) + \left( {\frac{{362.50 \times 2R \times 1}}{{100 \times 3}}} \right) \cr & = 33.50 \cr & \Rightarrow \left( {2175 + 725} \right)R = 33.50 \times 100 \times 3 \cr & \Rightarrow \left( {2175 + 725} \right)R = 10050 \cr & \Rightarrow \left( {2900} \right)R = 10050 \cr & \Rightarrow R = \frac{{10050}}{{2900}} = 3.46 \cr & \therefore Original\, rate = 3.46\% \cr\end{align}

 Question 4
If the simple interest on Rs. 1 for 1 month is 1 paisa, then the rate percent per annum will be =?
 A 12% B 10% C 8% D 6%