ShmoopTube

00:03

[Coop and Dino singing]

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When someone's running a business, they generally hope that their yearly profits will keep rising [Hot air balloons rising[

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higher and higher, like a hot air balloon that's just taking off.

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However, every now and then they might find that their profits are actually falling, like [Hot air balloon falling back to the ground]

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a hot air balloon that was attacked by some very anti-balloon birds.

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Those things are vicious.

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And they make some cool protest signs. [Birds flying in the sky holding protest signs for no fly zone]

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But not to worry: we have some mathematical tools to help us understand decreasing profits.

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We don't have any tools to help you with your hot air balloon, though. [Child using a parachute to land]

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Hopefully you brought a parachute.

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Let's think this through with an example.

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Helga runs Helga's Hot Air Balloon rides, and last year the company made a profit of

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$60,000. [Helga delighted at her profits]

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However, due to recent bird attacks, it looks like profits will decrease one quarter

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this year.

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So exactly how much should she expect to make in profits this year?

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This also raises the question about what to do about those pesky birds. [Big bird swooping in scaring the smaller birds]

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Maybe hire bigger birds to scare 'em off?

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We don't know.

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We do math, not animal control.

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The first thing we need to do is figure out what one quarter of $60,000 is. [One quarter of 60,000 calculation on a notepad]

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We've seen this kind of thing before.

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All we have to do is multiply one quarter by 60,000…

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…and we know that this gives us 15,000.

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So far so good.

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Now, when we were finding a fractional increase to profits, we would take our product… [Coop pointing to the chalkboard displaying fractional increase]

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…and add it to the original number.

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More money got added to the pile, and everyone was happy. [Money added to a pile and people at the table smiling]

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However, when we're finding a fractional decrease to profits, we instead take our product…

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…and remove it from the original number, by subtraction.

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Sure, subtracting isn't nearly as fun as having lots of money, but hey, gotta play the cards [Money taken away from the pile while people look angry]

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you're dealt.

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So let's think about how that applies to Helga.

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Since last year's profit was $60,000…

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…we need to subtract our product, $15,000…

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…leaving us with $45,000.

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Sure, it's not quite as much as $60,000, but hopefully it'll be enough for Helga to figure [Birds attacking a hot air balloon]

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out a solution to her ongoing bird problem.

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Maybe she can invest in some anti-bird drones.

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Let's just hope she's not dealing with birds with some hacking skills. [Drone chasing Helga away]

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The world of hot air ballooning is not for the faint jeart]

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