Question

The population of a town is 50,000. It decreases by 50 per thousand per year. Find out the population after 2 years.

• A. 45000
• B. 45125
• C. 42000
• D. 42125

Answer 1

The correct option is B

45125

Since the population is decreasing , we use the depreciation formula to find the population after two years

$A=P(1-\frac{r}{100)}{)}^n$

where, Initial population = $P$, Rate = $r$% per annum, Time = $n$ years and the population after n years = $A$

Rate of percent(r) = $r=\frac{50\times 100}{1000}=5$% ($\because$ percentage is calculated for fifty per thousand)

Population after 2 years$=P(1-\frac{R}{100}{)}^T=50000(1-\frac{5}{100}{)}^2=50000(1-\frac{1}{20}{)}^2=45125$