slot machines are flow video games, with winning determined by electronic ralldoll number generators. In the old days, slot machines were like this: . You pull the lever to spin the three wheels; . Each wheel had 20 symbols (some of which could be duplicates), all equally likely to show when the wheel stopped spinning, and Each of the three wheels was independent of each other. Suppose the middle wheel has three bells among the 20 symbols, and the left and right wheel have one bell each. a. You will the jackpot if all three wheels show bells. What is the probability of winning the jackpot? b. What is the probability that the wheels stop with exactly two bells showing