Probability

[151AND8TH]

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What is the probability of rolling 2 dice and getting a 4? getting two 4 would be 1/36 -- I am thinking the chances of getting one 4 would be greater than that -- since you would have 2 chances...right??

 

[joonkimdds]

What is the probability of rolling 2 dice and getting a 4? getting two 4 would be 1/36 -- I am thinking the chances of getting one 4 would be greater than that -- since you would have 2 chances...right??

bah....what am i thinking....🙁
i will come back to answer this after i wake up.

 

[Lonely Sol]

What is the probability of rolling 2 dice and getting a 4? getting two 4 would be 1/36 -- I am thinking the chances of getting one 4 would be greater than that -- since you would have 2 chances...right??

Well the question is basically asking that if you have 2 separate dice in your hand you roll them together, what are the chances that the sum will be 4?

so, you could roll:
1....3
3....1
2....2
2....2

Now you know that you can come with 4, four different ways. So, the the chances of you rolling a 4 will be:
4/(6^2)
4/36 = 2/18 = 1/9

 

[REH]

Lonely,

I'm not sure that two should be included twice. The number two occurs on each die only once. In other words:

1...3 = 1/6 * 1/6 = 1/36
2...2 = 1/6 * 1/6 = 1/36
3...1 = 1/6 * 1/6 = 1/36

= 3/36
= 1/12

Cheers,

REH

 

[joonkimdds]

By the way, is it correct to use 6x6 =36?
6 dots from 1st dice can be paired with
6,5,4,3,2,1 from the 2nd dice
5 dots can have 5, 4 dots can have 4.....etc.

6+5+4+3+2+1 = 21
and then 2nd dice can have the same
so 21 x 2 = 42 different ways.
if this is incorrect and someone says, 6-6, 5-5, 4-4, 3-3,2-2,1-1 were
counted twice so i have to subtract 6 from 42 ==> 36 different ways
then we shouldn't count 2-2 twice for the answering this question.

I haven't studied math for a very long time so i am not sure.
maybe we should count 2-2 twice and 1-3 twice, but then i think it should be
4/42 = 2/21 = 0.095

 

[AdidasPete]

REH is correctamundo...
There are 36 possible dice combinations. From 1-1 through 6-6. (Think of it as a 6 by 6 square Punnett square that you use for bio recombination problems). There are 3 combinations that produce the required answer, 3-1, 2-2, and 1-3. The 2-2 roll only gets counted once in dice rolls. so you get a 3/36 or 1/12 prob of getting you four... Now get back to the craps table and study up...

 

[151AND8TH]

Lonely, I was asking for the #4 not the total (sum) of the dice that adds up to 4 -- so if you throw 2 dice, what is the chance that one of them will be a four.. i know that for both to be 4 your chances will be (1/6)*(1/6)=1/36.

Also, it seems as if the chances of getting a #4 from 2 dice would be greater then the chance of getting a #4 from just 1 dice (1/6).. I am thinking it would be 1/3?..................

Epiphany-- epiphany!!!! the answer IS 1/3 or 2/6 chances.. because your number of favorable outcome went up and the number of possible outcome didnt change.. so if you trhew 3 dices, you would have a 50% chance of getting the #4 that we're talking about


for the other question-- (sum of 4).. REH is correct, you would only have 1/12 chances.. you can see that by doing a grid and it would show you that:
the sum of 4 can be obtained in 3 combinations
the sum of 5 can be obtained in 4 combinations
the sum of 6 can be obtained in 5 combinations
ect..

Thanks guys!!