ShmoopTube

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Alright shmoopy question of the day, comin' at ya...

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A wig store is having a sale on genuine, 100% rat-fur wigs, where the first wig purchased costs $10.

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...the total cost in relation to the number of wigs bought is given by the plot below.

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What would be the total cost if a person buys 15 rat wigs at this store?

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And here are the potential answers...

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Try them yourself first before you look forward.

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So... this question is asking us to decipher a graph and recognize a pattern --

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then throws a few curveballs at our heads.

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Which hopefully won't knock the wigs off our skulls.

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Let's think aloud a bit -- the FIRST wig costs 10 bucks.

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Note the 2 here at the bottom of the graph -- that's the second wig -- the TOTAL

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cost of BOTH wigs is 15 bucks.

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So if the first was 10 then the second must have cost 5 bucks more.

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Look at the 3 -- it's telling us that 3 wigs cost 20 bucks and if we look forward,

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a pattern comes clear here...

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...the first wig was 10 bucks but each subsequent wig is 5 bucks.

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So if we have 15 wigs in TOTAL that we are buying, 14 of 'em cost us

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5 bucks each or a total of 70 dollars...

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...and then we have to add that first expensive one for 10 bucks

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so that the total for ALL of 'em costs 80 bucks.

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And note in the answer set there are all kinds of answers that are... close.

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The RIGHT answer, though, is 80 or C.

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Now we can all look dashing in our affordable new rat-fur wigs.

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