Two friends, Sam and Joseph, are often late for class. Joe is
late with p = 0.20 and Bill is late with p= 0.30. Because they
are coming from the same location, their arrival times are
correlated. Given that Joe is late, the conditional probability
that Bill is also late is 0.80.
What is the probability that both arrive to class on time? Pr
(not late) = ______________
Following from problem 3 above, assume that lateness on any
day is independent of lateness on the previous day. What is
the probability that Bill is late three days in a row?
Pr = ___________
Two friends, Sam and Joseph, are often late for class. Joe is
late with p = 0.20 and Bill is late with p= 0.30. Because they
are coming from the same location, their arrival times are
correlated. Given that Joe is late, the conditional probability
that Bill is also late is 0.80.

What is the probability that both arrive to class on time? Pr