ShmoopTube

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Here’s another shmoop du jour for you and your brain...

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The governor of New York has decided to build a Not-So-Great-Wall-of-China…town.

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Of course, he wants to make it stand out, so he feels it should be colorful…

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The following graph shows the relationship between the number of gallons of paint needed

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to cover a wall, and the size of the wall (in square feet). 

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It is estimated that an average person can paint 120 square feet of wall space in an hour.

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Approximately how many gallons of paint

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is needed if eight people paint the wall together for an hour?

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And here are the potential answers...

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The first thing we have is a graph that tells us how much paint it takes to cover a certain

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number of square feet in area.

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Then, we’re asked to find how much paint eight people would need to paint at full capacity

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for an hour. The question tells us how much one person can paint in an hour…

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…so to find out how much area is covered by eight people, we can just multiply that by eight.

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8 times a 120 is 960…

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…so we know that in an hour, eight people can cover 960 square feet with paint.

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Now, we just have to convert 960 feet into the number of gallons of paint we’ll need.

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But since we don’t have exact numbers, we’ll have to estimate a little bit.

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The easiest way to do this on a graph is to look at intersections.

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We can see that the y-coordinate of 900 square feet is about equal to 2.5 gallons of paint…

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…and the x-coordinate of 3 gallons of paint is about the halfway mark between 900 and

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1200 square feet covered, which is roughly 1050 square feet.

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We know that 960 is between 900 and 1050,

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so our x-coordinate has to be greater than 2.5 and less than 3.

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The only answer choice that meets those criteria is (B), 2.7 gallons.

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As in… “Brown might have been better.”

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