a box in a certain supply room contains four 40-w light bulbs, five 60-w light bulbs, and six 75-w light bulbs. suppose that three bulbs are randomly selected. (a) what is the probability that exactly two of the selected bulbs are rated 75-w? (b) what is the probability that one bulb of each type is selected? (c) what is the probability that all three of the selected bulbs have the same rating?