
#1
Jan814, 03:45 PM

P: 99

Hey,I am making an app that counts probabilities in c++(win32){for those who knows}.
I have found three formulas of equation,but I need some help for one. For example we have a die,and we hit it 6 times. Can we count with an formula,the probabilities to have the number "5",three times exactly?(no less,no more) Thanks!!! 



#2
Jan814, 04:27 PM

Sci Advisor
P: 5,941

Use the binomial theorem.
k out of n with probability p of success on one roll (q=1p), is p^{k}q^{(nk)}n!/{k!(nk)!}. Your example: n = 6, k = 3, p = 1/6. 



#3
Jan914, 06:45 AM

P: 99

Can you explain more because I hear about that first time?
Or you could send me a tutorial?? 



#4
Jan914, 03:21 PM

Sci Advisor
P: 5,941

app that counts probabilities in c++
http://en.wikipedia.org/wiki/Binomial_distribution
Start here. Google "binomial distribution" to get more links. 



#5
Jan914, 03:30 PM

P: 99

Yea,I found an intersting site called "Math is fun",and I undestood it,but how I can count probabilities with that?




#6
Jan914, 04:08 PM

Sci Advisor
Thanks
P: 2,972

You cast the die six times, so there are ##6^6## equally likely sequences of results. Because they are equally likely, the probability of getting any given sequence is one in ##6^6##. How many of these sequences include exactly three fives? 


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