find sample space
step 1: pick one marbles from 5. there are 5 ways (5C1)
step 2: toss a cube one time, 1-6. there are 6 ways (6C1)
total ways (sample space) = 5x6 = 30
... multiplication rules
find event
step 1: pick one blue marbles from 2. there are 2 ways (2C1)
step 2: toss a cube one time, get only 1 or 2. there are 2 ways (2C1)
total ways for event = 2x2 = 4
p(event) = n(event)/n(sample space) = 4/30
