1. In the California Fantasy 5 lottery, a player pays $1 for a ticket and selects 5 numbers from the numbers 1 through 39. If they match exactly three of the five numbers drawn, they receive $15. What is the probability of selecting exactly three of the five numbers drawn?
2. The winning combination in the Florida lottery consists of six numbers drawn from the numbers 1 through 53. What is the probability that a single ticket has no matches?
3. Suppose that a study produced the following results: Out of a group of 80 people who took Sleep Helper before going to bed, only 20 of them had difficulty falling asleep. Out of a group of 80 people who took a placebo before going to bed, 25 of them had difficulty falling asleep. Calculate the absolute and the relative risk reduction due to taking Sleep Helper. Also, calculate the number of people who must take Sleep Helper in order for one person to be helped?