probability
posted by MW .
Seven chips labeled A B C D E F and G are placed in a jar. Five chips are drawn at random.
Find the probability thatc chips A and B are selected.

number of ways to draw 5 chips from 7 = C(7,5)
= 21
number of ways to draw the A and B and any 3 others
= 1xC(5,3) = 10
so prob of A and B among the 5 = 10/21