Answer:
55%
Explanation:
the question is asking what is the probability he has 8 hours of sleep GIVEN he has had 0 cups.
we find the number where 0 cups and 8 hours meets. that is 12.
divide that by P(0 cups). P(0 cups) is total of 0 cups, ie 22.
so answer is (12/72) / (22/72)
= 12/22
= 6/11
= 0.5454
= 55% to nearest whole percent