How many gallons should she buy?.

eddy2017

eddy2017

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Hi, need a little big help with this/
Sarah wants to paint her living room (12 ft x 16 ft with B ft ceilings). (The ceilings are not gonna be painted) The paint she selects will cover 400 square feet per gallon. How many gallons should she buy?.

I have to find the area of the 4 walls.
Do you think I can use this formula to give me the total area to be painted?
A=2(l+w)h.
thanks,
eddy
 
eddy2017 said:
Hi, need a little big help with this/
Sarah wants to paint her living room (12 ft x 16 ft with B ft ceilings). (The ceilings are not gonna be painted) The paint she selects will cover 400 square feet per gallon. How many gallons should she buy?.

I have to find the area of the 4 walls.
Do you think I can use this formula to give me the total area to be painted?
A=2(l+w)h.
thanks,
eddy
Click to expand...
Yes, you're exactly right. You can imagine unfolding the walls to make one big rectangle with width equal to the perimeter of the room. Or, you could just find each wall's area separately and add them, which is more work.

I imagine, though, that the ceilings are 8 feet high, not B.
 
Dr.Peterson said:
Yes, you're exactly right. You can imagine unfolding the walls to make one big rectangle with width equal to the perimeter of the room. Or, you could just find each wall's area separately and add them, which is more work.

I imagine, though, that the ceilings are 8 feet high, not B.
Click to expand...
Right, my bad. 8ft high ceilings.
Thank you. I'll go ahead and post my work
 
Living room dimensions
[math]12 by 16 ft with 8 ft high ceilings[/math].
Plugging in formula,
[math]A=2(l+w)*h[/math][math]A=2(12+16)×8[/math][math]A=2×28×8[/math][math]A=448ft^2[/math]The paint will cover 448ft^2.
The problem says that the paint will cover 400 ft^2,
448÷400=1.12
So She should by 1 gallon and a half or two gallons to have enough to cover the area.
 
lev888 said:
Why not 1.12? The problem does not state that paint can be purchased only in 1 gallon or half-gallon increments.
Click to expand...
Because you always want to have spare paint around which matches the original. Of course it never matches completely because the original paint fades, but I am getting too far on a tangent...
 
I followed what I have seen so far in problems involving paint. They always round up to the next gallon. I think because of what blamocur pointed out.
 
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eddy2017 said:
I followed what I have seen so far in problems involving paint. They always round up to the next gallon. I think because of what blamocur pointed out.
Click to expand...
No, because in real life, you cannot go to Home Depot and buy 12% of a gallon. Lev is ABSOLUTELY right as a matter of pure mathematics. In terms of applied mathematics, you may have additional constraints that must be taken into consideration. How would your answer have changed had they said that you could buy paint in quarts or gallons?
 
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