A paint that is sold only in gallon containers covers 200 square

[BTGModeratorVI]

A paint that is sold only in gallon containers covers 200 square feet per gallon of paint. How many gallons of the paint must be purchased to cover the walls of an auditorium that is 40 feet long, 25 feet wide, and 12 feet high if the areas of the windows and doors are ignored?

A. 4
B. 8
C. 16
D. 32
E. 60

Answer: B
Source: GMAT prep

[Brent@GMATPrepNow]

A paint that is sold only in gallon containers covers 200 square feet per gallon of paint. How many gallons of the paint must be purchased to cover the walls of an auditorium that is 40 feet long, 25 feet wide, and 12 feet high if the areas of the windows and doors are ignored?

A. 4
B. 8
C. 16
D. 32
E. 60

Answer: B
Source: GMAT prep

Here's an idea of what the auditorium looks like:


So the total surface area to be painted = (12)(25) + (12)(25) + (12)(40) + (12)(40)
= 300 + 300 + 480 + 480
= 1560 square feet

Given: 1 gallon of paint covers 200 square feet

1560/200 = 7.something
So, 7.something gallons of paint are needed.
This means we must purchase 8 gallons of paint

Answer: B

Cheers,
Brent