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Population of a town increase 2.5% annually but is decreased by 0.5% every year due to migration. What will be the percentage increase in 2 years?
Answer & Solution
Correct Answer:
Option
B
Net percentage increase in Population = (2.5 - 0.5) = 2% each year.
Let the Original Population of the town be 100.
Population of Town after 1 year = (100 + 2% of 100) = 102.
Population of the town after 2nd year = (102 + 2% of 102 ) = 104.04
Now, % increase in population = $$\frac{{4.04}}{{100}} \times 100 = 4.04\% $$ Mind Calculation Method: 100 == 2% Up(1st year) ==> 102 == 2%Up(2nd year) ==> 104.04 % population increase in 2 years = 4.04%.
Now, % increase in population = $$\frac{{4.04}}{{100}} \times 100 = 4.04\% $$ Mind Calculation Method: 100 == 2% Up(1st year) ==> 102 == 2%Up(2nd year) ==> 104.04 % population increase in 2 years = 4.04%.
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LoginBy applying this formula we can get a desired result : -
(a + b) + ab / 100 here for a and b the value will be same as 2
(2+2) + 2*2 / 100 = 4.04
now decrease in 2 year 0.5+0.5%=1
now 5-1%=4
now decrease in 2 year 0.5+0.5%=1
now 5-1%=4
2.5 - 0.5 = 2.
if you are doing mind calculation then this little calculation would be understandable. Think think you understand it.