I'm completely stuck on this question and I'm pretty sure my answers are wrong. Any help would be much appreciated!!
Undergraduate economists can either do a single Honours degree
or a joint Honours degree. Their society has a party which they all
attend. They are joined by other joint Honours students who are not
doing any economics at all. 55% of people are doing a joint Honours
degree and 65% of people are doing some economics. 100 people
attend the party.
a) What is the probability that a single Honours student at the party is
also doing economics?
b) What is the probability that an economist is a single Honours
student?
c) What is the probability that a joint Honours student is studying
economics?
d) What are the odds that a student is a joint Honours economist?
e) Five joint honours students leave the room. What is the probability
that they are a mixed group of economists and non-economists?