Q asked by lecturer: trainees 80% female, females 90% college-educ., males 78% colleg

First, (1) asks you to draw a tree diagram. Do you know what a "tree diagram" is? The will be branching into "male" and "female" and, for each of those branches, further branching into "attended university" and "did not attend university".

For (2) what is the probability that a selected person is female? And if that is true, what is the probability that female attended university. Your lecturer clearly expects you to know that P(A and B) is equal to P(A) times P(B given A).

In (3) you are told that the person is female. So what is the probability she is attended university?

(4) Do you know what "independent" means here? If not look up the definition! Roughly speaking it means that knowing one thing is true does not change the probability that the other is true. Suppose you know a person is male. What is the probability he attended university? Suppose you know a person is female. What is the probability she attended university? Was your answer to those two questions different?

(5) Do you know what "mutually exclusive" means? Two events are "mutually exclusive" if one happening means the other cannot happen. If a person is female does that mean she cannot have attended university? If a person is male does that mean he cannot have attended university?
 
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