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Algebra and Functions Videos 30 videos
CAHSEE Math Algebra and Functions: Drill Set 1, Problem 1. At this rate, what is the total cost of 10 songs?
CAHSEE Math Algebra and Functions: Drill Set 1, Problem 2. Which of the following represents the statement?
CAHSEE Math: Algebra and Functions: Drill Set 1, Problem 3. What equation fits the description?
CAHSEE Math 6.5 Algebra and Functions 197 Views
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Description:
Algebra and Functions: Drill Set 6, Problem 5. How long will it take Snow White to consume the pie from the old hag?
Transcript
- 00:03
Here's the shmoopiest question you've likely heard in the last ten minutes...
- 00:07
Snow White just ran into an old woman who baked her an entire apple pie. How lucky is she?
- 00:12
The pie has a radius of 8 inches.
- 00:15
SW knows she can consume a mini-pie with a radius of 4 inches in five minutes.
- 00:20
At this rate, how long will it take her to consume the pie from the old hag?
Full Transcript
- 00:24
The area of a circle, remember, is A equals pi times radius squared...
- 00:29
And here are the potential answers...
- 00:31
Before we spoil the ending, hit pause and try it yourself.
- 00:34
This question is asking us to derive the area of a circle from a formula...
- 00:38
...and then apply that derivation to a rate-of-eating problem.
- 00:42
So... first, the question gives us the area of a circle formula -- pi times radius squared.
- 00:48
We first have to calculate the area of the first 4 inch pie and then the 8 incher.
- 00:52
Pi-r squared of the first gives us 3.14 times r squared which is 16 or about 50;
- 00:59
And pi-r squared of the second gives us 3.14 times 8 squared which is 64 or about 200.
- 01:07
Now we can set up a ratio.
- 01:09
50 square inches takes 5 minutes; so 200 square inches should take... how many minutes?
- 01:15
Well, check out the ratio here. We have four times the square inchage, so...
- 01:19
...we should also have 4 times the... time.
- 01:22
Or, 20 minutes. Answer C.
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