# Probability Formula?

#### tobermory

##### New Member
There are 3 balls in a bag, one red, two blue.

Therefore, there is a 33.33% (Cell A1) chance of picking the red ball, and a 66.66% (Cell A2) of picking a blue ball.

Would there be a formula to calculate the probability in a 'Best of X' race?

So for instance, what would be the probability of picking 2 red balls, before 2 blue balls? (Best of 3)

or the probability of picking 7 red balls, before 7 blue balls? (Best of 13)

This question always assumes there are always 3 balls are always in the bag. So it's always a 33.33/66.66% chance.

Thanks!

#### palaeontology

##### Active Member
Re: Probabilty Formula?

You would be able to achieve this through using .... =Binomdist or a combination of these

will play with it now

#### palaeontology

##### Active Member
Re: Probabilty Formula?

see if this is what you need ...

Place the headings "best of", "minimum # of success needed", "# combinations", "probability" in cells F24, G24, H24, I24

in F25 enter ... 3
in G25 enter ... =ROUNDDOWN(F25/2+1,0)
in H25 enter ... =COMBIN(F25,G25)
in I25 enter ... =BINOMDIST(G25,F25,1/3,FALSE)

in F26 enter ... =F25+1 and drag down as far as needed

drag down cells G25, H25 and I25 as far as needed

you should have the correct probabilities in decimal form

Kind regards

Chris

#### palaeontology

##### Active Member
Re: Probabilty Formula?

Was that what you wanted ?

Kind regards,

Chris