Probability

Started by Oraisteach, February 01, 2013, 09:19:59 PM

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Oraisteach

So, I'm playing an intellectually straining game of Yahtzee.  I'm looking for a large straight.  I have five dice, and on the first roll I get 2, 2, 3, 4, 5.   I keep 2, 3, 4, 5 and have two more rolls with a single die to hit a 1 or a 6.  What is the probability of my hitting a 1 or 6 in those two rolls?  It's 2/3, right, or am I way off?  What, instead, of having just 2 rolls I have 3 rolls?  What would the probability be then?

upmonaghansayswe

#1
Quote from: Oraisteach on February 01, 2013, 09:19:59 PM
So, I'm playing an intellectually straining game of Yahtzee.  I'm looking for a large straight.  I have five dice, and on the first roll I get 2, 2, 3, 4, 5.   I keep 2, 3, 4, 5 and have two more rolls with a single die to hit a 1 or a 6.  What is the probability of my hitting a 1 or 6 in those two rolls?  It's 2/3, right, or am I way off?  What, instead, of having just 2 rolls I have 3 rolls?  What would the probability be then?

Probability of getting a 1 or 6 in either roll is 1/3 (4/12 - favourable outcomes/possible outcomes).

Probability of getting a 1 or 6 in the first roll and then the other one in the second roll is 1/18 (1/3 x 1/6)

And it would still be a third with 3 rolls (6/18).

seafoid

Quote from: upmonaghansayswe on February 01, 2013, 09:49:38 PM
Quote from: Oraisteach on February 01, 2013, 09:19:59 PM
So, I'm playing an intellectually straining game of Yahtzee.  I'm looking for a large straight.  I have five dice, and on the first roll I get 2, 2, 3, 4, 5.   I keep 2, 3, 4, 5 and have two more rolls with a single die to hit a 1 or a 6.  What is the probability of my hitting a 1 or 6 in those two rolls?  It's 2/3, right, or am I way off?  What, instead, of having just 2 rolls I have 3 rolls?  What would the probability be then?

Probability of getting a 1 or 6 in either roll is 1/3 (4/12 - favourable outcomes/possible outcomes).

Probability of getting a 1 or 6 in the first roll and then the other one in the second roll is 1/18 (1/3 x 1/6)

And it would still be a third with 3 rolls (6/18).
But if you pray to St Jude and promise publication the odds change.

Tony Baloney

Have Yahtzee in the house which has never been opened. Any good? Too hard for wains?

dec

Two rolls 5/9

Three rolls 19/27

upmonaghansayswe

#5
Quote from: dec on February 01, 2013, 10:17:59 PM
Two rolls 5/9

Three rolls 19/27

What's the sums? Yeah getting to repeat something that's 1/3 will increase your odds. I'm wrong.

armaghniac

Probabilities

1 or 6 first throw 1/3
not 1 or 6 followed by 1 or 6     2/3 x 1/3 = 2/9
1 or 6 on both throws 1/3 x 1/3
nothing 2/3 x 2/3 = 4/9

useful outcome 5/9 nothing 4/9


If at first you don't succeed, then goto Plan B

Oraisteach

Tony, the game's a fun diversion.  How old are the kids?

St. Jude is now looking like the best probabilty . . .

Tony Baloney

Quote from: Oraisteach on February 01, 2013, 11:10:42 PM
Tony, the game's a fun diversion.  How old are the kids?

St. Jude is now looking like the best probabilty . . .
8 and 6 (and 4).

PadraicHenryPearse

Quick question.

Is it better to have two chances of being drawn out of a draw of 500. 5 tickets drawn.

Or

Is it better to have one entry but do it on two different occasions.

Thanks.

Maiden1

#10
Quote from: dec on February 01, 2013, 10:17:59 PM
Two rolls 5/9

Three rolls 19/27
For you not to hit straight it has to be not 1 or 6 (2/3) followed by not 1 or 6 (2/3) so odds of not winning (2/3)×(2/3)=(4/9). So odds of winning (5/9).

3 goes odds of Not win (2/3)×Not win (2/3)×Not win (2/3)=8/27.  Odds of winning then 1-(8/27)=19/27
There are no proofs, only opinions.

PMG1

Quote from: PadraicHenryPearse on October 07, 2017, 11:14:42 AM
Quick question.

Is it better to have two chances of being drawn out of a draw of 500. 5 tickets drawn.

Or

Is it better to have one entry but do it on two different occasions.

Thanks.
[/quote
Either way your chances are 2/500 so both the same

Maiden1

Quote from: PMG1 on October 07, 2017, 01:04:54 PM
Quote from: PadraicHenryPearse on October 07, 2017, 11:14:42 AM
Quick question.

Is it better to have two chances of being drawn out of a draw of 500. 5 tickets drawn.

Or

Is it better to have one entry but do it on two different occasions.

Thanks.
[/quote
Either way your chances are 2/500 so both the same
Not quite.

2 tickets in same draw odds

2/500 or 0.004

Different draws odds of winning are 1-(499/500)×(499/500) or 0.003996.

If bought all 500 tickets odds be 1.  If bought 1 ticket in 500 draws not guaranteed to win.
There are no proofs, only opinions.

ONeill

Quote from: PadraicHenryPearse on October 07, 2017, 11:14:42 AM
Quick question.

Is it better to have two chances of being drawn out of a draw of 500. 5 tickets drawn.

Or

Is it better to have one entry but do it on two different occasions.

Thanks.

Depends if you're related to the chairman or not.
I wanna have my kicks before the whole shithouse goes up in flames.

PadraicHenryPearse

Quote from: ONeill on October 07, 2017, 01:51:32 PM
Quote from: PadraicHenryPearse on October 07, 2017, 11:14:42 AM
Quick question.

Is it better to have two chances of being drawn out of a draw of 500. 5 tickets drawn.

Or

Is it better to have one entry but do it on two different occasions.

Thanks.

Depends if you're related to the chairman or not.

If I was related, there would by no need for the question.