# Probability question?

If you have a deck of cards (52) and you take two cards out, but replaced the first one after picking it, what is the probability of picking a seven (then returning it to the deck) & then picking an Ace?

(Homework assignment, I need to know how to do this for a test tomorrow).

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There are 4 sevens in the deck of 52 so the probability of picking a seven is

1/13

The probability of picking an ace is the same....1/13

So the probability of both occurring is (1/13)(1/13)=1/169

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• The probability of picking any particular rank is 4/52 = 1/13. The probability of picking a particular rank then another (with replacement in between) is given by multiplying probabilities:

prob = (1/13)*(1/13) = 1/169 <----

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• Anonymous
5 years ago

P(pick a 7, return it to deck, then pick an ACE) = (4/52) * (4/52) = (1/13)² = 1/169

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• hjnjj

• Thanks for your well thought out answer. It really helped (-:

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