ykaiim wrote:

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

OA is B and OE is:

Let the starting population be X. There will be change in population by a factor of \frac{6}{5} every year. So, in 4 years the population becomes:

(\frac{6}{5})^{4x} = 2.0736X

So, after 4 yrs, population become >double X.

I have a doubt: The population becomes double before the completion of 4th yr. So, it mean 3 yrs are passed not 4.

Experts please comment.

Bunuel i also believe that the correct answer is 3 because it is not taking full 4 years, approx 3 years 10 months.

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