Question

If the population of a town is decreasing by 4% per year and started with 12,500 residents, which of the following is its projected population in 10 years?

1-9,230
2-76
3-18,503
4-8,310

Answer 1

Answer:

The population of town after 10 years is 8300 unit .

Step-by-step explanation:

Given as :

The rate of decrease of population of town = 4%

The initial population of town = 12,500 unit

Let The population of town after 10 years = P

So ,

The population of town after n years = initial population × $(1-\frac{Rate}{100})^{n}$

Or, The population of town after 10 years = 12,500 × $(1-\frac{4}{100})^{10}$

Or,  The population of town after 10 years = 12,500 × $(0.96)^{10}$

∴ The population of town after 10 years = 12,500  × 0.664 = 8300 unit

Hence The population of town after 10 years is 8300 unit .  Answer

Answer 2

The population after 10 years will be 8310 approximately.

Option - 4

SOLUTION:

Given that, the population of a town is decreasing by $4\%$ per year and started with 12,500 residents,

We have to find its projected population in 10 years. We can use the formula  

$\text { present population }=\text { previous population } \times\left(1-\frac{\text {rate}}{100}\right)^{\text {times\times period }}$

Then, population after 10 years $=12500 \times\left(1-\frac{4}{100}\right)^{10}$

$\begin{array}{l}{\Rightarrow 12500 \times(1-0.04)^{10}} \\\\ {\Rightarrow 12500 \times 0.96^{10}} \\\\ {\Rightarrow 12500 \times 0.6648} \\\\ {\Rightarrow 8310.407\rightarrow 8310.407\approx 8310}\end{array}$

ROUNDING OFF RULES:

Step 1: First, look at the digit to the immediate right of rounding off the digit

Step 2: If that digit is less than 5, do not change the rounding digit but drop all digits to the right of it.

Step 3: If that digit is greater than or equal to five, add one to the rounding digit and drop all digits to the right of it.