Answers:
- Problem 7) 1/26
- Problem 8) 1/13
- Problem 9) 10/13
- Problem 10) 1/2
- Problem 11) 11/13
- Problem 12) 3/13
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Explanations:
Problem 7)
There are 2 red aces (hearts, diamonds) out of 52 cards total, so 2/52 = 1/26 is the probability of picking a red ace.
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Problem 8)
There are 4 kings out of 52 cards total, so 4/52 = 1/13 are the odds of picking a king.
This is the same as say focusing on one suit (eg: clubs) and finding the probability of pulling out a king.
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Problem 9)
There are 3 face cards per suit (Jack, Queen, King) so 3*4 = 12 face cards in all. The odds of picking a face card are 12/52 = 3/13. That makes 10/13 the odds of not picking a face card, since 3/13+10/13 = 1.
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Problem 10)
The answer is 1/2 because half of the cards are red.
You could say 26/52 = 1/2 since there are 26 red cards out of 52 cards total.
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Problem 11)
There are 4 copies of '2' and 4 copies of '3', so there are 4+4 = 8 cards we want to avoid. The probability of picking either of them is 8/52 = 2/13. The odds of not picking any of these cards is 11/13 (refer to problem 9).
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Problem 12)
We have 4 copies each of '7', '8' and '9'
That gives 4*3 = 12 cards total we want to pick.
So 12/52 = 3/13 is the answer.