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Description:
Statistics, Data, and Probability I: Drill Set 5, Problem 5. What is the probability that, on the second draw, a vowel will be chosen?
Transcript
- 00:03
Here's a shmoopy question for you...
- 00:06
There is a crisis at Sesame Street.
- 00:08
The residents there are in urgent need of 2 letters.
- 00:11
According to the laws of the land, those letters must be chosen at random from an alphabet
- 00:16
set consisting of both upper- and lowercase letters.
Full Transcript
- 00:20
If, on the first random draw, the letter capital 'E' was chosen and eliminated from the Cookie
- 00:26
Monster's garbage can of available letters... ...what is the probability that, on the second
- 00:32
draw, a vowel will be chosen?
- 00:34
Assume the letters 'y' and 'Y' are consonants...
- 00:38
And here are the potential answers:
- 00:43
Life may look easy on the Street but it isn't always.
- 00:46
The puppets there wrestle with big ideas. And sometimes with each other.
- 00:51
So what is this question really asking? It's a probability question with a twist on the
- 00:55
total set of possible choices.
- 00:57
The basic alphabet has 26 letters -- but the twist is that this problem treats capital
- 01:03
letters different from small letters...
- 01:05
...kinda like fancy computer password log ins these days.
- 01:08
So there are 52 total choices of letters in the mega set of possibilities.
- 01:13
To now get to the answer, we have to assess the "damage" given by the other twists
- 01:17
the problem throws at us.
- 01:18
First of all, the capital E is removed -- it's a vowel and it's also one of the 52 choices.
- 01:25
So now we know the denominator has to have 51 in it, not 52.
- 01:30
We know that there are 5 vowels in the alphabet -- but there are 10 choices if we can count
- 01:35
both a capital and a small letter. And we have removed a capital E from the possible
- 01:40
picks moving forward.
- 01:41
So there are just 9 vowels left as possible
- 01:44
picks over the total set of 51... ... so our answer is 9 over 51. Choice C.
- 01:51
Or should that be... choice... lowercase c? Uh oh, we're feeling overwhelmed...
- 01:55
Where's Elmo when you need him?
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