Roll a fair die 6 times and read the number on the upper face. (a) What’s the probability of observing all possible numbers 1 to 6? (b) What’s the probability of observing three 6-s and three 1-s? (c) What’s the probability of observing two 1-s, two 3-s and two 5-s? (d) What’s the probability of observing six even numbers?