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3 replies to this topic

### #1 jamie bickers

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Posted 08 January 2008 - 09:34 PM

If you throw a dice once the cance of getting six is 1/6
If you throw a dice twice the cance of getting six is 2/6
If you throw a dice three times the cance of getting six is 3/6
If you throw a dice four times the cance of getting six is 4/6
If you throw a dice five times the cance of getting six is 5/6

Does this mean that if you throw a dice 6 times you are garantied 6?
Of course it doesn't but how come theareticly the chance is 100% when practicly it isn't.
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### #2 bonanova

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Posted 08 January 2008 - 10:06 PM

If you throw a dice once the cance of getting six is 1/6
If you throw a dice twice the cance of getting six is 2/6
If you throw a dice three times the cance of getting six is 3/6
If you throw a dice four times the cance of getting six is 4/6
If you throw a dice five times the cance of getting six is 5/6

Does this mean that if you throw a dice 6 times you are garantied 6?
Of course it doesn't but how come theareticly the chance is 100% when practicly it isn't.

Spoiler for Only your first statement is true.

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Vidi vici veni.

### #3 spoxjox

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Posted 08 January 2008 - 10:09 PM

If you throw a dice once the cance of getting six is 1/6
If you throw a dice twice the cance of getting six is 2/6
If you throw a dice three times the cance of getting six is 3/6
If you throw a dice four times the cance of getting six is 4/6
If you throw a dice five times the cance of getting six is 5/6

Does this mean that if you throw a dice 6 times you are garantied 6?
Of course it doesn't but how come theareticly the chance is 100% when practicly it isn't.

Your odds aren't quite right.

If you throw a die (btw, singular is 'die', plural is 'dice') you have a one in six chance of getting a specified number, e.g. six. That means you have five chances in six of not getting a six.

In two dice rolls, your chances of not getting a six are 5/6 for the first roll and 5/6 for the second roll, giving you total odds of (5/6) * (5/6), or 25/36, of not getting a six. Thus, your odds for getting at least one six are one (100% odds) minus the odds of not getting at least one six: 1 - 25/36, or 11/36. Note that this is slightly smaller than 2/6 (= 12/36), as you had said above.

In six dice rolls, your odds of not getting a six are therefore (5/6)^6, or 15625/46656, which is just a bit greater than 1/3 odds. Therefore, your odds of rolling at least one six are one minus this amount, which as a percent is 66.5%.
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### #4 caecae

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Posted 08 January 2008 - 10:12 PM

Ok. well i may not be right but here it goes any way. well i read it a few times and there is a problem because even if you role a die 6 time the prob is going to remain at 1/6 chance for each role but the as you roll the die more times your chance of gettin a six will increase. so i did the math because it was really bugging me and if you roll the dice 6 times it is actually a 40% chance or a 2.4/6 chance of getting a six. i got this from my stat class.
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