SOLUTION: the population of a city is estimated to be at 432000 after 2 years.if population growth is 20% per annum,what is the current population

Algebra ->  Percentage-and-ratio-word-problems -> SOLUTION: the population of a city is estimated to be at 432000 after 2 years.if population growth is 20% per annum,what is the current population      Log On


   

Question 295708: the population of a city is estimated to be at 432000 after 2 years.if population growth is 20% per annum,what is the current population
Answer by CharlesG2(834) About Me  (Show Source):
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the population of a city is estimated to be at 432000 after 2 years.if population growth is 20% per annum,what is the current population
current * 1.20 going forward (1.20 is 120% is 6/5)
current * 5/6 going backward (the reciprocal of 120%)
If we are going forward 2 years:
432000
432000 * 1.20 (20% growth) = 518400 (end of year 1)
518400 * 1.20 = 622080 (end of year 2)
If we are going backward 2 years:
432000
432000 * 5/6 = 360000 (1 year prior)
360000 * 5/6 = 300000 (2 years prior)