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## #1 2006-01-18 08:53:43

laila
Guest

### probability-whats the chances sum1 is gonna help

i gotta small problem here on probability....

Two fair dice are thrown. Find the probability that the sum on both dice :

is equal to 6

is at most 6

is at least 6

Thanks guys

## #2 2006-01-18 09:21:31

MathsIsFun
Registered: 2005-01-21
Posts: 7,664

### Re: probability-whats the chances sum1 is gonna help

The numbers are small enough to actually count them.

There are 36 possible combinations (6×6)

For the sum to be 2, there is only 1 combination: 1-1
For the sum to be 3, there are 2 combinations: 1-2 and 2-1
For 4, there are 3 combinations: 1-3, 2-2, and 3-1
For 5, there are 4 combinations: 1-4, 2-3, 3-2, and 4-1
For 6, there are 5 combinations: 1-5, 2-4, 3-3, 4-2, and 5-1

So, for the sum to equal 6, the probability is 5/36
For the sum to be at most 6, the probability is (1+2+3+4+5)/36 = 15/36

I will leave the last one for you!

"The physicists defer only to mathematicians, and the mathematicians defer only to God ..."  - Leon M. Lederman

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## #3 2006-01-18 12:26:45

laila
Guest

### Re: probability-whats the chances sum1 is gonna help

thanx.

i needed the method by using the probability equations. Or binomial distribution.
Thats what the paper requires.

if would be grateful if someone could reply with solution done by using probability equation

Thanks

## #4 2006-01-18 18:13:15

kempos
Member
Registered: 2006-01-07
Posts: 77

### Re: probability-whats the chances sum1 is gonna help

you can't use binomial distriution with this problem :-(

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