If in a certain population, people are born at an average rate of 9 people every 2 seconds and people die at...

[BTGmoderatorLU]

Source: GMAT Prep

If in a certain population, people are born at an average rate of 9 people every 2 seconds and people die at an average rate of 3 people every 2 seconds, by approximately how many people does the population increase in 1 day?

A. 17,280
B. 25,920
C. 129,600
D. 259,200
E. 388,800

The OA is D

[Scott@TargetTestPrep]

Source: GMAT Prep

If in a certain population, people are born at an average rate of 9 people every 2 seconds and people die at an average rate of 3 people every 2 seconds, by approximately how many people does the population increase in 1 day?

A. 17,280
B. 25,920
C. 129,600
D. 259,200
E. 388,800

The OA is D

Solution:

The growth rate, i.e., the difference between the number of people born and those who have died, per second, is:

9/2 - 3/2 = 4.5 - 1.5 = 3

So the growth rate is 3 x 3600 x 24 = 259,200 per day.

Answer: D