A survey was conducted of students asking about their usage of marijuana in the last year (Never, Occasional, Regular) and the amount of alcohol and/or marijuana usage by their parents (Neither, One, Both). Here is a table of data. Student Usage Never Occasional Regular Parental Usage Neither 141 54 60 One 68 44 51 Both 17 11 19 The conditional probability that the parents use one of alcohol or marijuana given a student never used marijuana is 68/226 = 0.30 = 30% 68/235 = 0.29 = 29% 68/445 = 0.15 = 15% 68%