Question

In a barn, there were 30 rats. 5 more rats entered the barn and 6 of the rats were eaten by the cats in one week. If 8 rats were born during the same period, and during the same time, 7 rats left the barn, find the resultant rat population in the barn at the end of one week.

Answer 1

Initial rat population = 30

Increase in population = Rats entered + Rats born

= 5 + 8

Decrease in population = Rats eaten + Rats left

= 6 + 7

Resultant population after one week = 30 + [(5 + 8) – (6 + 7)]

= 30 + (13 – 13)

= 30