Question

The annual rate of growth in population of a certain city is 8%.I its present population is 196830,what was the population 3 years ago.

Answer 1

let 3 years ago the population of city be ' x '

1st year :
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increase in population = 8% of x

= 0.08x

population of city till 2nd year :

= x + 0.08x = 1.08x

2nd year:
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increase in population 8% of 1.08x

= 0.08 × 1.08x = 0.0864x

present population:
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population of city till 3rd year :

population = 1.08x + 0.0864x

= 1.1664x

population of city till 3rd year = present population

but according to given statement, present population of the city = 196830

1.1664x = 196830

x = 168750

Answer:
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population of city 3 years ago was

168750
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