Binomial Trials by JoeMath.com
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Here is a formula to calculate the probability of an event given the following conditions:
C(N,k) = __
C(3,0) =1
C(3,1) = 3
C(3,2) = 3
C(3,3) = 1
(.3)k(.7)N - k =
(.3)3(.7)0 = .027
(.3)2(.7)1 = .063
(.3)1(.7)2 = .147
(.3)0(.7)3 = .343
Try it in the calculator below.
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p =
C(N,k) =
q =
Pr(X = k) =
What if you wanted to find Pr( X >= 10) ? You would want to find Pr( X = 0) + Pr( X = 1) + + Pr( X = 10) Too many to do by hand so try this...
Let X be a random variable associated with an experiment. X is the number of "successes" in the N trials of the experiment. Toss a fair coin 40 times and let heads represent "success". Find the probability of getting at least 20 heads. i.e. Pr( X >= 20)
Starting
k = Ending k =
N =
Pr(X >= k) or Pr( a <= X <= b)