Question Background

Question

You want to paint a room. You assume no doors and windows and that your paint will go on "perfectly." At the store you realize that your paint can only be purchased in gallon cans at $43.50 per gallon and that your paint has a density of 1.23g/mL ( from information posted on the manufacturer’s web site).
Question:
a) If your room is 10' X15' X 8' and you put 0.1mm of paint on the walls, how much paint do you need?
b) After you start painting you realize that your walls are so heavily textured that it has 60% more surface area that you calculated. Do you have enough paint and if not how much more will you need... actual amount and cans of paint.
c) If you realize that you have 40 sq ft of doors and windows, do you still need to purchase additional paint? Explain your answer.
d) If you spill 75 mL of paint and you realize that you have lost 100 mL of paint because it is in your brush, roller, and paint tray and so unusable, how many feet of wall coverage did you lose?
e) Does this "wastage" cause you to have to buy more paint? Explain.

Answer 1

0.1 mm is tiny thickness. Typo?

Well 1 gallon = 3.785 Liters = 3785 mL
and 1 meter = 3.281 feet

area of room walls = 2*10*8 + 2*15*8 = 160 + 240 = 400 ft^2
400 ft^2 * (1 meter/ 3.281 ft)^2 = 37.2 meters^2

volume to cover = 37.2 m^2 * (0.1 /1000) m = 3.72 ^ 10^-3 m^3 =3.72 mL
( note, I think that 0.1 should be like 1 mm)

Multiply by 1.6 for texture problem ----> 5.95 mL

The doors and windows reduce the area of course

I give up, the assumed paint thickness just makes the rest hopeless. A gallon would cover the house at 0.1 mm or even 0.16 mm

Answer 2

@ NEddie
A math problem under any other name still is a math problem. I gave up after the second "what if" scenario.