If each year the population of the country grows by 20%, how many years will elapse before the population of the country doubles?
A) 3
B) 4
C) 5
D) 6
E) 7
OA3
A) 3
B) 4
C) 5
D) 6
E) 7
OA3
if an amount x increases by a fraction a/b then the final amount = x * (1 + a/b)^n.
here the fraction is 20/100 ,plugging in from the asnwer to see when x doubles
1 gives = 1.2x not enough
2gives = 1.44x not enough
3 gives = 1.728x not enough
4 gives = 2.0736x enoguh because x has doubled
but the question asks how many years will elapse before the population doubles..now we know that the population doubled befoe the completion of 4 years..maybe 3 years and 10 months..so the answer is 3.
