ShmoopTube

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[Dino and Coop singing]

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So you know how to divide fractions…congratulations! [Confetti falls on student]

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But will this new skill do you any good in the rough-and-tumble world of business, where

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people are more interested in making loads of money by any means necessary… [People looking angry and holding up money and notepads]

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…rather than sitting around, quietly doing math?

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Well…yeah, actually.

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This kind of math's really important in business. [Students walks across classroom yelling and holding math workings]

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After all, yelling angrily will only get you so far.

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To see how this works, let's take a look at a couple of examples.

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Kim's an accountant at a toy company, but just because there are toys all over the place

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doesn't mean that her work's all fun and games. [Kim is knocked over by an RC car]

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Right now, she's in a bit of a pickle.

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She's looking over the files for their sled division, and appropriately enough, profits [Kim's body is replaced by a pickle]

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are going downhill.

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She knows that over the last two years, profits have decreased by a total of four fifths.

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But she can't find the records that tell her how much profits fell each year.

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If she knows that each year's profits decreased by an equal value relative to where profits [Kim thinking about the problem]

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were two years ago, by how much did profits decrease each year?

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She could spend the next few days rifling through the company's basement, trying to [Kim looking through filing cabinets]

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find the missing information...

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Or she could just do some math.

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We vote math.

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Less chance of running into mice and dust bunnies. [Kim's face turns green]

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Since the profits decreased by the same amount relative to where profits were the first

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year, we can take the total drop, of four fifths…

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…and divide it by two, for each of the two years that passed.

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Luckily we know a thing or two about dividing fractions, so we multiply four fifths by the

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reciprocal of two, one half…

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…which gives us four tenths.

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And once we divide the common factor of two out of the numerator and the denominator… [Fraction workings on a whiteboard]

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…we're left with our final answer: two fifths.

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It might have taken a few steps, but it was a lot quicker than a few hours in the basement.

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And a lot less dusty, too. [Kim sneezes and a big dust cloud appears]

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It turns out Kim has some more incomplete data to wrestle with.

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Over the last three years, the jack-in-the-box division saw their profits go up seven eighths.

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Again, though, there are some gaps in her data. [Arrows point to gaps in the graph]

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If she knows that each year's profits increased by an equal value relative to where profits

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were three years ago, by how much did profits increase each year?

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Unfortunately, she's unlikely to find the answer in a jack-in-the-box. [Kim winds the handle on the box]

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Well, unless the answer is: "a creepy clown face." [A clown jumps out the box and scares Kim]

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Time for more fraction division.

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Since the profits increased by the same amount relative to where profits were that first

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year, we can take the total increase, of seven eighths…

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…and divide it by three, for each of the three years that passed.

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So we multiply seven eighths by the reciprocal of three, one third…

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…which gives us seven twenty-fourths.

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With no common factors, we're done! [The missing data is written on the chart]

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And bonus: no one got a crippling fear of clowns that hide in boxes. [Kim chucks the Jack-in-the-box away and it explodes]

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