ShmoopTube

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[Dino and Coop singing]

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Ooh, sweet bar graph!

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We've seen a bunch of bar graphs in our time and that?

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That's one to be proud of. [Boy holding up a bar graph grinning]

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However, what if there's some sort of change in the data?

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You might have to make some adjustments.

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But don't worry: it's not like bar graphs and written in stone. [Boy making adjustments to his graph]

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And if you do make your bar graphs with stone, you should probably think of using something

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else. [Bar graph written on a boulder and woman pushes it around]

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Y'know…like… paper?

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Just a thought.

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Let's see how this works with an example.

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Ben works as an intern at Bouncy Balls Inc., a company that makes all sorts of bouncy balls. [Ben throwing a pink ball and catching it]

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The hours aren't great, but he does get to take home as many bouncy balls as he wants,

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so…we'd call that a win.

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For one project, he had to make a bar graph, showing projections of the company's profits [Profit projections for Ben's company]

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for the next five years.

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Based on the info he got, it seemed like profits would be up a quarter every year.

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However, it turns out the company is actually expecting a drop in profits of one fifth in [Man holds out a sign for a drop in profit in year 3 and Ben gasps]

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year 3.

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Does this mean Ben's graph will go in the trash…

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…and that Ben might end up there, too? [Ben falls into a trash can]

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Not necessarily…

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Heh, just kidding, Ben.

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You wouldn't fit in there anyway.

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But Ben will definitely need to make some changes to his bar graph, so let's help him [Ben using a laptop to make changes to his bar graph]

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out.

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The change that Ben has to deal with is that rather than increasing by a quarter from year

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2 to year 3…

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…profits should actually drop by one fifth.

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So let's take a look at those year 2 profits, and do some calculations. [Profit projections for Ben's company and arrow points to year 2]

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If we look at the graph, we see that for year 2, profits were $10,000.

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So let's multiply that by one fifth, and subtract the result from $10,000. [Year 2 profits multipled by 1 fifth]

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We're sure you can do this calculation in your sleep, but we'd definitely recommend [Boy sleeping whilst doing math calculations]

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doing most of your math while you're awake.

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It's tough to see the paper when your eyes are closed. [Boy holding a scribbled piece of paper from writing while sleeping]

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So, on to the calculations: one fifth times $10,000 is $2,000…

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…and when we subtract that from the original $10,000, we get $8,000.

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So once Ben adjusts his graph so that year 3 is at the right height, will he be done?

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Nope. [Ben waves his arms in the air celebrating]

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Sorry Benny, no rest for the wicked.

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Remember, his graph was based on the idea that profits would go up by a quarter every

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year… [Ben stops celebrating goes back to his graph]

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…so after changing the bar for year 3, he also has to adjust all the years that came

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after it: year 4 and year 5.

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An intern's work is never done.

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For year 4, we take the profits from year 3, multiply by a quarter…

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…and then add this to the year 3 profits, giving us a total of $10,000.

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For year 5, we do almost exactly the same thing, taking the profits from year 4, multiplying [Adjusted graph for the 5 year profit projections]

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by a quarter…

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…and then adding this to the year 4 profits, giving us a total of $12,500.

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So once Ben adjusts the heights of his bars to hit this new data, he'll be ready to present [New adjusted bar graph and a hand giving a thumbs up]

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his new bar graph.

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And as long as he doesn't, say, knock over a huge crate of bouncy balls, the presentation

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should go fine. [Ben knocks over a crate and bouncing balls fall out]

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Ugh, Ben!

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What'd we just say not to do??

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This guy never listens. [Bouncing balls bouncing in the classroom]

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