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Statistics and Probability Videos 134 videos
SAT Math: Statistics and Probability Drill 1, Problem 2. If the four largest numbers in the set were doubled, what would happen to the median...
SAT Math 1.4 Statistics and Probability. If two standard 6-sided dice are rolled, what is the probability that the sum of the dice will be gre...
SAT Math 1.5 Statistics and Probability. If Silas draws one card, then places it in his pocket and draws another, what is the probability that...
SAT Math 5.5 Numbers and Operations 182 Views
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Description:
SAT Math 5.5 Numbers and Operations
Transcript
- 00:02
Here’s your shmoop du jour, brought to you by Handshakes.
- 00:06
The best way to pass along bacteria to someone you’ve just met.
- 00:09
Six people are in a room.
- 00:11
If everyone shakes hands one time with each other, how many handshakes take place?
- 00:18
Okay, so either some important business deal is about to go down…
Full Transcript
- 00:21
…or else the annual Sweaty Palm Convention is in town.
- 00:24
Purell, anyone?
- 00:26
All right – we’re looking for the total number of handshakes.
- 00:29
First, each of the 6 people has to shake hands with the 5 other people.
- 00:34
To count these handshakes, let’s multiply 6 by 5... 30.
- 00:39
Oops. By doing that, we’ve over counted… by a lot.
- 00:43
With this method, we’re basically counting person A shaking hands with person B as one handshake
- 00:49
and person B shaking hands with person A as a totally separate handshake.
- 00:54
In reality, when 2 people shake hands with each other, that only counts as 1 handshake.
- 01:00
To be more specific, our number is actually double the real number of handshakes actually happening,
- 01:06
so divide that 30 by 2 and get 15.
- 01:09
That’s a lot of handshaking.
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