The population of a town is decreased by 15% and 20% in two successive years. The present and decreased percent of population are respectively |
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a) |
85%, 15% |
b) |
80%, 20% |
c) |
68% , 32% |
d) |
32%, 68% |
The population of a town is decreased by 15% and 20% in two successive years. The present and decreased percent of population are respectively |
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a) |
85%, 15% |
b) |
80%, 20% |
c) |
68% , 32% |
d) |
32%, 68% |
Let the population before 2 years be Population after one year=
Again it decreases by 20%, therefore population after 2 years =
∴ Present population (after this year)=68% and % decrease in population =
Alternative Method (I) (Using corollary (2) of T-1):
The decrease %=
∴ Population remains after two years=68% of the original
Alternative Method (II):
Let the population 2 years ago=100 and there are two successive decrease 15% and 20% respectively.
(-15)
∴ Change (decrease) in population = 100-68=32%