Binomial probability - Wikipedia, the free encyclopedia
For the first, I would take the probability of rolling no 6's and subtract that from 1.
I have looked through this topic for almost an hour trying to find this question already answered, forgive me if it has been.
If I have a fair six sided die and I roll it 20 times
what is the chance i will roll a 6 at least once?
What is the chance I will roll a 6 only once?
I dont need the answer just the formula for the answer.
Binomial probability - Wikipedia, the free encyclopedia
For the first, I would take the probability of rolling no 6's and subtract that from 1.
The probability of rolling a 6 at least once = probability of rolling a 6 followed by a non-6, plus probability of rolling a non-6 followed by a 6, plus probability of rolling a 6 followed by a 6:
1/6 x 5/6 + 5/6 x 1/6 + 1/6 x 1/6.
Which as Undefined points out is the same as 1 minus the probability of a non-6 followed by a non-6.
Probability fo rolling a 6 just once can be calculated from the first two terms of the above.