SOLUTION: There are 5 chemistry, 6 physics, and 7 math teachers in a school. If 3 teachers are selected randomly, Find the probability that at least one is a math teacher.

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Question 1074320: There are 5 chemistry, 6 physics, and 7 math teachers in a school. If 3 teachers are selected randomly, Find the probability that at least one is a math teacher.
Answer by Edwin McCravy(20065) About Me  (Show Source):
You can put this solution on YOUR website!
P(at least one math teacher is chosen)

1 - P(no math teacher is selected) = 

1 - P(all 3 were from the 11 non-math teachers) =

1 - (11 non-math teachers CHOOSE 3)/(18 teachers CHOOSE 3) =

1 - (13C3)/(18C3) =

1 - 286/816 = 

816/816 - 286/816 =

530/816 =

265/408

Edwin