a painter calculated the amount of paint needed to cover the

Question

a painter calculated the amount of paint needed to cover the four walls of a certain windowless room, but mistakenly assumed the walls were nine feet tall, when they were actually 10 feet tall. his initial calculation indicated that he would need 18 cans of paint. if each can of paint holds enough to cover 25 sq. feet, what is the actual number of can needed to paint the room?

Karthik · Answer

its 20 Cans.....

25 x 18 = 450 sq ft is the total area....
sum of the lengths of the rooms sides=50ft from above......since height is 9ft...

so the ht remaining fixed as 10ft. the area being 500 sqft...we need 20 Cans...

Yan · Answer

20

{  x 10} / 25 
If you write it in a fraction way, you get 20 very easily. 
25 / 25 = 1; 18 / 9 = 2; 2 x 10 = 20

ian7777 · Answer

agree with yan. no reason to multiply 18x25 if you're going to divide by nine later on. I just built the math out like this:

25(18)=9x

Originally, I wondered what to do about the room having 4 walls, and if it was a square room or a rectangular room, but it doesn't matter. You can "unfold" the walls and get one long rectangle, 9 height, unknown length. In case anyone else has the same question.

So x=50, and so 10(50) = 500

500/25 = 20

ceg2002 · Answer

the room being a square or a rectangle was what was stumping me. thanks for demystifying it.

ywilfred · Answer

got the same answer:

area of the 4 walls (9 feet high) = 18*25 = 450 sq feet
area of 1 wall (9 feet high) = 450/4 = 112.5
So the base of the wall is 112.5/9 = 12.5 feet long

So a 10 feet high wall has an area of 125 sq feet
4 10 feet high walls will have an area 500 sq feet
so the number of cans of paint required is 500/25 = 20

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a painter calculated the amount of paint needed to cover the

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