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The population of a town is decreased by 15% and 20% in two successive years. The present and decreased percent of population are respectively

a)

85%, 15%

b)

80%, 20%

c)

68% , 32%

d)

32%, 68%



Question ID - 55700 | SaraNextGen Top Answer

The population of a town is decreased by 15% and 20% in two successive years. The present and decreased percent of population are respectively

a)

85%, 15%

b)

80%, 20%

c)

68% , 32%

d)

32%, 68%

1 Answer
127 votes
Answer Key / Explanation : (c) -

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%

127 votes


127