Percentage - Aptitude MCQ Questions and Solutions with Explanations

Answer: Option B

Let the initial price of the commodity be 100.

After 50% increase in price, It will become,
100 ------50% increase----> 150.
Now, we have to reduce the consumption to keep expenditure 100.

Increase in price= 150 - 100 = 50
We have to reduce the consumption,
$$\eqalign{ & = \frac{{50}}{{150}} \times 100 \cr & = \frac{1}{3}{\text{ or 33}}{\text{.33}}\% \cr} $$

Other Method:
Here, we use, Final product constant graphic.
100 ==50% up== 150===33.33% down===>100
Consumption Reduce = 33.33% = $$\frac{1}{3}$$

Answer: Option C

Here we can use the compound interest based formula,
$$\eqalign{ & {\text{Population after }}n{\text{ years}} \cr & = P \times {\left[ {1 + {\frac{r}{{100}}} } \right]^n} \cr & {\text{Population after 2 years}} \cr & = 50000 \times {\left[ {1 + {\frac{4}{{100}}} } \right]^2} \cr} $$
Population after 2 years = 54080

Alternatively,
we can use, net percentage change graphic as well,
50,000------4%↑---→ 52,000---- 4%↑---→ 54,080.
Then, population after 2 years= 54,080.
In this calculation, we need to find 1% of 50,000 first, which is easily calculated by dividing 50,000 by 100.