Expert: Sherman D. - 9/5/2008

Question

Bob has to paint a room which is 12.90m long, 9.654m wide and 10.523m high. The ceiling and the walls must be painted. It takes $.55 in paint to cover 1 sq meter of surface. How much does he spend on paint to finish the job? about all i know is that it is not a volume question. if you could tell me how you arrived at your answer that would be great.

Answer
here is what you have to do, you have to use the Surface Area for a Rectangular Box, then you have to subtract the area of the floor.

however since i don't know the dimensions of the floor, your problem will have 3 different answers.

T = 2(ab + ac + bc)

T = 2((12.9 * 9.654) + (12.9 * 10.523) + (9.654 * 10.523))

using www.quickmath.com to make this quick

T = 723.745 - ((12.9 * 9.654) or (12.9 * 10.523) or (9.654 * 10.523))

T1 = 599.208 m^2
T2 = 587.998 m^2
T3 = 622.156 m^2

since it costs .55 per 1 m^2, all you have to do is multiply by .55

$T1 = $329.56
$T2 = $323.40
$T3 = $342.19

just keep in mind that i had to round to the nearest cent.

Here's the site with info. http://mathforum.org/dr.math/faq/formulas/faq.parallelepiped.html