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Re: For each player's turn in a certain board game, a card is drawn. 3/4 [#permalink]
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lichting wrote:
Hi Bunuel,
I did it this way, please correct me. idk what did I miss out
Quote:
what is the probability that at least four of the cards drawn are marked with a square?


- 4 squares = 5C4 * (1/4)^4 * (3/4)^1
- 5 squares = 5C5 * (1/4)^5 * (3/4)^0
Total prob = (21/4) * (1/4)^4


We want the probability that out of 5 cards drawn 4 OR 5 are squares.

\(P(SSSSC)=\frac{5!}{4!}*(\frac{1}{4})^4*(\frac{3}{4})=\frac{15}{4^5}\).

\(P(SSSSS)=(\frac{1}{4})^5\).

Therefore the overall probability is \(\frac{15}{4^5}+\frac{1}{4^5}=\frac{1}{4^3}\).

This is explained here: https://gmatclub.com/forum/for-each-pla ... l#p1139227

In the highlighted part in your solution it's not clear how you got the numbers there and why are multiplying instead of adding.
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Re: For each player's turn in a certain board game, a card is drawn. 3/4 [#permalink]
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Re: For each player's turn in a certain board game, a card is drawn. 3/4 [#permalink]
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