Two boxes have colored balls in them. Box A has 3 blue and 7 red balls in it, box B has 2 blue and 1 red. (a) Three balls are selected without replacement from box A and one ball is selected from box B. What is the chance that at least one of these balls is blue? (b) A random box is selected, and then 10 balls are selected with replacement all from that random box. Find the chance that there are exactly 4 blue balls in the 10 draws.