Question 1074320
<pre>
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</pre>