30 balls, 15 red, 5 yellow, 5 green, 5 blue
In general, probability = # ways you want / # of ways total
a) P(red) = 15/30 = 0.5 >> you get an average of 0.5 red balls per draw.
300 draws * 0.5 red / draw = 150 red balls.
b) P(yellow or blue) = 10/30 = 1/3 >> you get an average of 1/3 yellow or blue balls per draw.
300 draws * 1/3 yellow or blue / draw = 100 yellow or blue balls.
c) P(not blue) = 25/30 = 5/6 >> you get an average of 5/6 not-blue balls per draw.
300 draws * 5/6 not-blue balls = 250 not-blue balls
d) P(pink) = 0/30. There are no pink balls.