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Geometry and Measurement Videos 88 videos

SAT Math 1.1 Geometry and Measurement
719 Views

SAT Math 1.1 Geometry and Measurement. What is the circumference of the circle?

SAT Math 1.2 Geometry and Measurement
246 Views

SAT Math: Geometry and Measurement Drill 1, Problem 2. If A = (0, 4), B = (-3, 2), and C = (1, 0), which point is in the interior of angle ABC?

SAT Math 2.3 Geometry and Measurement
267 Views

SAT Math 2.3 Geometry and Measurement. Find the length of AB.

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SAT Math 10.5 Geometry and Measurement 192 Views


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Description:

SAT Math 10.5 Geometry and Measurement. How many rotations does each tire make?

Language:
English Language

Transcript

00:03

Here’s your shmoop du jour, brought to you by “riding a motorcycle.”

00:07

It’s…just like riding a bike. But with the added near-certainty of serious injury.

00:13

A bicycle that has tires with a diameter of 2 feet travels half a mile.

00:18

How many rotations does each tire make? There are 5,280 feet in one mile.

00:24

Round answer to the nearest whole number.

00:27

So what we’re looking for is the number of rotations…

00:31

Well, cleverly, let’s call that… n.

00:33

That n for…number of rotations.

00:37

All right, we want to know how many times the full circle rotates over the course of its journey,

00:42

so the circumference of the tire… times n… equals a half a mile.

00:48

If there are 5,280 feet in a mile, then in a half mile that's...

00:53

5,280 over 2...that's 2,640.

00:58

We know the circumference of a circle is diameter times pi...

01:03

…so 2 – the diameter of our tire…times pi times n…equals 2,640.

01:11

We want n by itself, so we divide both sides of the equation by 2 pi to get n equals 2,640 over 2 pi.

01:21

Now it’s time to put our calculator to work.

01:24

2,640 divided by 2 pi comes out to 420.38…

01:31

or, when rounded to the nearest whole number… 420 rotations.

01:36

Wow… you had so much fun counting tire rotations you barely even remember how you got here.

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