Help me out

Hi Sharee7a,

Are you currently studying for the GMAT or for some other type of Test? I ask because this question doesn't have the 'feel' of a typical GMAT question. In addition, since you didn't include 5 answer choices, I would assume that this question is from a general 'math book' and not necessarily for a standardized Test. If you are studying for the GMAT, then there are plenty of reputable materials that you could be using. That having been said, here's how you can answer this question:

We're told that Alberto has decided to paint his dining room, paint comes in 1 litre cans and the paint in one can will cover an area of approximately 24 square metres. The dining room is 4 m x 6 m x 3.5 m high, there is just one window which is in one of the long walls and is 1.5 m x 2 m and all of the walls, door and ceiling are to be painted with the same type of paint. Approximately 20% of the wall area to be painted is wood which will need a SECOND coat of paint. We're asked for the minimum number of cans of paint that Alberto should buy to paint the room as described.

To start, we need to know the areas of the 4 walls and ceiling:
Ceiling = 4 x 6 = 24 m^2
Short walls = (2)(4 x 3.5) = 28 m^2
Long walls = (2)(6 x 3.5) = 42 m^2
Total area = 24 + 28 + 42 = 94 m^2

Next, there are some 'adjustments' to this total:
The window = (1.5 x 2) = 3 m^2 --> we will NOT paint the window, so we have to subtract this area
The 2nd coat = 20% of the WALLS = (20% of 70) = 14 m^2 --> we will paint this area a second time.

Total painting area = 94 - 3 + 14 = 105 m^2
1 can of paint covers approximately 24 m^2. With 4 cans of paint, that would cover (4)(24) = 96 m^2, but that would NOT be enough paint. Thus, we will need a 5th can.

Final Answer: 5 cans

GMAT assassins aren't born, they're made,
Rich