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CAHSEE Math 5.4 Statistics, Data, and Probability I 174 Views
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Description:
Statistics, Data, and Probability I: Drill Set 5, Problem 4. What is the probability that the pointer creates a new winner?
Transcript
- 00:03
Here's a shmoopy question for you...
- 00:06
The following fair spinner is spun one time.
- 00:09
According to Norse legend, God spins it every time a new human child is born,
- 00:14
to determine whether they're going to be a winner... or a loser.
- 00:18
Aw, and you thought we had free will.
Full Transcript
- 00:21
What is the probability that the pointer creates a new... winner?
- 00:24
And here are the potential answers...
- 00:29
OK, that FAIR spinner thing again.
- 00:31
For these kinds of problems, FAIR just means that what you see is what you get...
- 00:35
...that is, the drawing is drawn to scale and the spinner isn't a Las Vegas scam to
- 00:39
cheat widows out of their savings by always landing on LOSE.
- 00:43
It's an odds or probability question -- but it's kind of a trick question as well.
- 00:47
Just look at the wheel. The total real estate taken up by "WIN" is ... large.
- 00:52
Like... "clearly over half" large.
- 00:54
Now look at the answers. Anything, uh.. stand out?
- 00:58
Yeah -- it's D.
- 00:59
No other answer could POSSIBLY work. It's D. We can just click it and move on.
- 01:04
Go ahead. Don't be shy. There's nothing wrong with using common sense.
- 01:07
BUT let's assume for a second that we actually want to learn how to solve this problem...
- 01:12
If we really wanted to get fancy, there's a few big fat clues here,
- 01:15
the biggest of which is the presence of right angle.
- 01:19
We know that a right angle is 90 degrees and
- 01:21
is a quarter of a circle... or 25% of it.
- 01:25
And that right angle is bisected with this line. That is, it's cut in half.
- 01:30
So each of these tiny slices is 12.5% of the circle or 45 degrees.
- 01:35
We have 3 LOSES of 12.5% which total to 37.5%.
- 01:40
The wins then have to be 100-37.5% or 62.5%.
- 01:45
We made the calculation but... we really didn't have to.
- 01:48
In fact, wasting so much time makes us feel like a real loser.
- 01:53
Wait a minute...
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