In: Statistics and Probability
Binomial or Poission Probabilities:A baker put 700 raisins into dough, mixed well, and made 100 cookies. You take a random cookie. What is the probability of finding at least five raisins in it?
Here, we use approximation to the Binomial distribution of the number of taisins in one cookie
The number of raisins X in one cookie is Binomial with n = 700 and p = 1/100 = 0.01, it is approximately Poisson with parameter np = 700*0.01 = 7. The proabability of finding at lest five raisins is
P(X 5) = 1 - P(X<5)
Poisson distribution:
...................X = 0,1,2,3,.......................
Where, Mean = = np = 700*0.01 = 7
P(X 5) = 1 - P(X<5)
P(X 5) = 1 - P(X = 0) + P(X = 1) + P(X = 2) + P(X = 3) + P(X = 4)
P(X 5) = 1 - 0.1730
P(X 5) = 0.8270
From the poisson table