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ACT Math 3.5 Plane Geometry 394 Views


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Description:

ACT Math: Plane Geometry Drill 3, Problem 5. How long would it take for the wheel to make two rotations?

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Transcript

00:02

For a good time solve this shmoopy question...

00:04

A circular wheel rotates 480 degrees in two minutes.

00:09

How long would it take for this wheel to make 2 complete rotations?

00:13

And here are the potential answers...

00:16

Well it's a plain vanilla ratio question really...

00:19

Something is to something as something else is to something else.

00:23

Key things to note: 1 full rotation is 360 degrees...

00:28

...so two rotations is 720 degrees...

00:31

...480 degrees is 2 minutes or...

00:35

...120 seconds as 720 degrees is to what?

00:40

So in this case we can just cross multiply here

00:43

and we take 480 time x equal 720 times 120.

00:48

So the base equation is 480X equals 86400.

00:52

Now divide both sides by 480 and get X equals 180 seconds.

00:57

That's x equals 180 divided by 60 seconds which is

01:03

3 minutes. Looks like C is our answer.