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SAT Math 8.1 Geometry and Measurement 179 Views
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Description:
SAT Math 8.1 Geometry and Measurement
Transcript
- 00:02
Here’s your shmoop du jour, brought to you by bicycles.
- 00:06
We’re still holding onto the patent for handlebar moustaches…
- 00:09
A bicycle that has tires with a diameter of 26 inches travels 2 miles.
- 00:13
Approximately how many rotations did each tire make?
- 00:17
And here are your potential answers…
Full Transcript
- 00:20
Oh, sure… the “bicycle” traveled 2 miles. No one at all was pedaling the dang thing.
- 00:25
Sheesh…credit where credit is due, guys…
- 00:27
All right, what have we got here?
- 00:29
Each tire of our bike has a diameter of 26 inches… well, that should help us find the circumference.
- 00:37
The formula we’re looking for is 2 pi r… or pi times d, because 2r is d.
- 00:42
We already have our d… so...
- 00:44
The perimeter of each tire is 26 pi inches… or 6.8 feet.
- 00:53
If we weren’t already a metric conversion whiz, the problem tells us that one mile equals 5,280 feet…
- 01:00
…so if our bike went TWO miles, then it went 10,560 feet. Which is…a lot of feet.
- 01:08
All right, well… we’ve got our perimeter… now we want to know how many times each tire
- 01:12
can turn that 6.8 feet over the course of its 2-mile run.
- 01:16
We take 10,560 divided by 6.8…
- 01:19
…and get roughly 1,550 rotations.
- 01:23
Option E.
- 01:24
Now I suppose you’re going to give the bike all the credit for solving this problem, too, aren’t you?
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