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 January 26th, 2010, 12:04 PM #1 Newbie   Joined: Jan 2010 Posts: 9 Thanks: 0 Cards problem Hi all, I am student and I have to solve a problem about cards. The problem is : "a. Find the probability the twentyfourth card to be 1. b. Find the probability to choose the first 1 after seven choices". And another , I know that when I have a pdf I equals with 1 so as to find a constant. But how can I find the integration of function (1/a)^x from -inf to inf. I made a matlab code and I took the answer piecewise([0 < a and a <> 1, Inf], [Otherwise, int((1/a)^x, x = -Inf..Inf)]) but I don't understand what it means. Could anyone help me ?? Thanks in advance
 January 27th, 2010, 12:51 AM #2 Newbie   Joined: Jan 2010 Posts: 9 Thanks: 0 Re: Cards problem Anybody ?? please
January 27th, 2010, 04:02 AM   #3
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Re: Cards problem

Quote:
 a. Find the probability the twentyfourth card to be 1.
To be 1 what? Is that "an ace"? Have the cards been shuffled, and the 24th chosen? The probability will be the same as if you chose the first card: 4/52.

Quote:
 b. Find the probability to choose the first 1 after seven choices.
Does this mean that you choose 8 cards, and the first seven are not aces, but the eighth is an ace?
(48/52)*(47/51)*(46/50)*(45/49)*(44/4*(43/47)*(42/46)*(4/45) = (44*43*42*4) / (52*51*50*49)

 January 27th, 2010, 04:25 AM #4 Newbie   Joined: Jan 2010 Posts: 9 Thanks: 0 Re: Cards problem Yes exactly. I am sorry but my engish is not good enough. Thanks a lot!!!

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