Word Problem 17 (Population of a town)
Problem 17 : During the first year the population of a town increases by 4% and during second year it diminished by 4%. If at the end of the second year its population was 2496 then initially the population was;
a. 2400 b. 2550 c. 25000 d. 2500
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Its a problem of compound interest ! On population we apply compound interest calculator or compound interest formula here – lets start!
Let us suppose;
y= population at the start of first year=?
R= rate of increase =4%
A=Population at the end of first year=?
T= Time duration in year=1
Since this is case of increase – we use +ve formula
Population diminish in the second year. Here,
(Since population at the end of the first year is now initial population for the second year ! )
R= Rate of decrease =4%
T= Time in years= 1
A=2496 (population at the end of second year)
Since this is case of decrease – we use -ve formula;
Putting values of variables for second year;
So, the population at the beginning of first year was 2500