Question 86638
Problem #1
If two cards are drawn without replacement from an ordinary deck, find the probabilities of the following results. 
The second is black, given that the first is a spade.
Since a spade was drawn and not replace there are 25 black cards in the deck
after the 1st draw.
Prob(black|spade} =25/51
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Problem #2)
Pam Snow invites 10 relatives to a party: her mother, 2 aunts, 3 uncles, 2 brothers, 1 male cousin, and 1 female cousin. If the chances of any one guest arriving first are equally likely, find the probabilities that the first guest to arrive is as follows.
a. An uncle or a cousin) 
P(uncle or cousin) = P(uncle) + P(cousin) = 3/10 + 2/10 = 1/2
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b. P(A male or a cousin) = P(male) + P(cousin) - P(male and cousin)
= 6/10 + 2/10 - 1/10 = 7/10
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c. P(A female or a cousin ) = P(female)+P(cousin)-P(female cousin)
= 4/10 + 2/10 - 1/10
= 5/10
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Cheers,
Stan H.