Jeff Miller

GMAT OFFICIAL GUIDE PS – Each year for 4 years, a farmer increased the number…

Each year for 4 years, a farmer increased the number…

This problem is testing us on exponential growth. The easiest way to navigate this problem is to set up a growth chart. We are given that the number of trees increased by ¼ each year. To determine the number of trees in a certain year, we multiply the number of trees from the previous year by 1.25, or 5/4. Let’s let x equal the number of trees at the beginning (of the first year) of the 4-year period.

We are given that there were 6,250 trees at the end of year 4 so we can set up the following equation:

(625/256)x = 6,250

625x = 6,250(256)

x = 10(256) = 2,560

Thus, there were 2,560 trees at the beginning of the 4-year period.

Answer: D