Jerry and Susan have a joint bank account. Jerry goes to the bank 20% of the days. Susan goes there 30% of…

Jerry and Susan have a joint bank account.
Jerry goes to the bank 20% of the days.
Susan goes there 30% of the days.
Together they are at the bank 8% of the days.
a. Susan was at the bank last Monday. What’s the probability that Jerry
was there too?
b. Last Friday, Susan wasn’t at the bank. What’s the probability that Jerry
was there?
c. Last Wednesday at least one of them was at the bank. What is the
probability that both of them were there?