ShmoopTube

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Shmoop, there it is… Shmoop, there it is...

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A quadrilateral has sides measuring 24.27 cm, 12.39 cm, 9.75 cm, and 25.99 cm.

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Which of the following expressions gives the best estimate as to the length

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of this quadrilateral's perimeter?

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Here are the potential answers…

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Ok, what is this question asking?

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Well yeah, it’s testing our mad rounding skillz…

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…but it’s also testing to make sure we can avoid traps.

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We should note that our four answer choices apparently went to… 4 very different schools.

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“A” rounds up or down to the nearest 10.

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B SOMETIMES rounds up, sometimes down, sometimes to the nearest 1, sometimes to the nearest 10...

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…and so on. They’re all over the map. In that case, we need to pay attention to

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how far away we’re getting from the original number.

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A goes down about 4, then down 2, the up almost nothin’, then up 4.

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All told, A is only about 2 off the correct total. Not bad.

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What about B? Down 4, down almost nothin’, up almost nothin’, and down 6.

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Combined, off by 10 or so. No good. C is down 4, down 2, up almost nothin’,

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up almost nothin’. Down 6 all day. A is still in the clubhouse with the lead…

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Finally, D. Up 6, up almost nothin’, up almost nothin’, down 6.

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There are some pretty big swings in there… but at the end of the day, it’s pretty spot on.

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Our answer is D.

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As in, “Duffer.”

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