Probability Distrubution- Binomal or geometric?

• May 5th 2010, 03:28 PM
questiongirl
Probability Distrubution- Binomal or geometric?
Hi guys....

i dunt realli understand how to do this question:

what is the probability that a triple for a dice..will occur within the first 5 rolls?

also, im not sure if this is Binomal or geometric...

• May 5th 2010, 04:25 PM
Anonymous1
Quote:

Originally Posted by questiongirl
Hi guys....

i dunt realli understand how to do this question:

what is the probability that a triple will occur within the first 5 rolls?

also, im not sure if this is Binomal or geometric...

A triple? Do you mean probability of a 3 in the first five rolls of a single dice?
• May 5th 2010, 05:13 PM
questiongirl
like getting triple 1s,2s,3s,4s..... for a dice. sorry i should have clarify the question.
• May 5th 2010, 05:23 PM
Anonymous1
Quote:

Originally Posted by questiongirl
like getting triple 1s,2s,3s,4s..... for $\color{red}{\text{a dice.}}$ sorry i should have clarify the question.

I assume you mean 3 dice, then?
• May 5th 2010, 06:02 PM
questiongirl
Quote:

Originally Posted by Anonymous1
I assume you mean 3 dice, then?

lol...i guess its getting late my typing has failed.. i mean 3 dice
• May 5th 2010, 07:08 PM
Anonymous1
$Pr(\text{triple}) = \frac{6}{6^3} = \frac{1}{36}$ since there are $6^3$ ways of rolling $3$ die, and only $6$ of the outcomes are triples.

The desired probability is:

$1- [{5\choose 0}(\frac{1}{36})^0(1-\frac{1}{36})^{5-0}] = 1- (\frac{35}{36})^5 = \frac{71}{1296}$

Oh, and yeah, it's a binomial.