Examveda

# Last year, the population of a town was x and if it increases at the same rate, next year it will be y. the present population of the town is

A. $$\frac{{x + y}}{2}$$

B. $$\frac{{y - x}}{2}$$

C. $$\frac{{2xy}}{{x + y}}$$

D. $$\sqrt {xy}$$

### Solution(By Examveda Team)

\eqalign{ & {\text{Let the present population of the town be }}P \cr & {\text{Using compound interest formula}} \cr & {\text{Then}}, \cr & P = x\left[ {1 + \left( {\frac{R}{{100}}} \right)} \right] - - - \,\left( i \right) \cr & {\text{And}}\,y = P\left[ {1 + \left( {\frac{R}{{100}}} \right)} \right] \cr & = P \times \frac{P}{x} - - - - \,\left( {ii} \right) \cr & {P^2} = xy; \cr & {\text{Hence}},\,P = \sqrt {xy} \cr}

## Comments ( 3 )

1. మణికుమార్ బండారు : Population always grow in compoundly. Ex- 100*10% = 10 in next year population = 100+ 10 so increse 110*10%= 11. in next year population 110 + 11 = 121 .......

2. I cannot understand it. Anyone can explain??

3. in the above formula why we using the compound interest formula

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