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SAT Math 1.5 Statistics and Probability 358 Views
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Description:
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 both cards will be blue?
Transcript
- 00:03
You can't handle the Shmoop!
- 00:07
Twelve cards are placed in a deck.
- 00:09
This kind of deck. Get that ship out of here.
- 00:11
Three of these cards are blue, four are green, and five are red.
- 00:16
If Silas draws one card, then places it in his pocket and draws another,
Full Transcript
- 00:20
what is the probability that both cards will be blue?
- 00:25
Round to the nearest tenth of a percent. And here are the potential answers…
- 00:30
Remember that the probability of a single trial is:
- 00:34
favorable divided by number of possible outcomes.
- 00:38
In the first trial, out of 12 cards, there are 3 blue cards.
- 00:42
There are 3 favorable outcomes, and 12 possible. This comes out to 3/12 or 1/4, or 25% chance.
- 00:49
Next, if we picked a blue card the first time, there would be 2 blue cards left in the deck,
- 00:54
and only 11 in total...
- 00:56
…which comes out to about 18%. To find the combined probability, we simply
- 01:01
multiply the two probabilities together.
- 01:04
.25 times .18 is .045…or 4.5%.
- 01:10
So our answer is (A).
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