math30
posted by alejandro .
Childrenâ€™s meals are being prepared for a large gathering. There is an equal number of chicken, hamburger, and fish meals. Each meal comes with a toy: a ball, a parachute toy, or a Frisbee. There are twice as many balls as Frisbees and an equal number of parachutes and Frisbees.
Determine the probability that a meal consists of chicken or fish and comes with a ball as the toy.

Prob(ball) = 2/4 = 1/2
prob(parachute) = 1/4
prob(frisbee) = 1/4
prob(chicken) = 1/3
prob(fish) = 1/3
prob( chicken or fish AND a ball)
= (1/3)(1/2) + (1/3)(1/2)
= 1/6 + 1/6
= 1/3