# Thread: Probability Distrubution- Binomal or geometric?

1. ## 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...

2. 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?

3. like getting triple 1s,2s,3s,4s..... for a dice. sorry i should have clarify the question.

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

5. 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

6. $\displaystyle Pr(\text{triple}) = \frac{6}{6^3} = \frac{1}{36}$ since there are $\displaystyle 6^3$ ways of rolling $\displaystyle 3$ die, and only $\displaystyle 6$ of the outcomes are triples.

The desired probability is:

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

Oh, and yeah, it's a binomial.