Question

A job fair was held at the Student Union. 25% of the students who attended received job offers. Of all of the students at the job fair, 40% were from the College of Business. Among these business students, 50% received job offers. Let J be the event that a student is offered a job. Let B be the event that the student is from the College of Business.

Requried:
a. Are events J and B independent? Why or why not?
b. Are events J and B mutually exclusive? Why or why not?
c. Joe, who is not a business student, attended the job fair. What is the probability that he received a job offer?
d. Another student, Samantha, received a job offer. What is the probability that she is a Business student?

Answer 1

A) Both events are not independent.

B) Both events are not mutually exclusive

C) 8.33%

D) 80%

Explanation:

A) Both events are not independent. This is because, If B occurs it means that it is very likely that J will occur as well.

B) Both events are not mutually exclusive. This is because it is possible for both events J and B to occur at the same time.

C) we want to find the probability that Joe who is not a business student will receive the job offer.

This is;

P(J|Not B) = P(J & Not B)/P(Not B)

Now,

P(J & Not B) = P(J) – (P(B) × P(J | B))

25% of the students who attended received job offers. Thus; P(J) = 0.25

40% were from the College of Business. Thus;

P(B) = 0.4

Among the business students, 50% received job offers. Thus;

P(J|B) = 0.5

Thus;

P(J & Not B) = 0.25 - (0.4 × 0.5)

P(J & Not B) = 0.25 - 0.2

P(J & Not B) = 0.05

Since P(B) = 0.4

Then, P(Not B) = 1 - 0.4 = 0.6

Thus;

P(J|Not B) = 0.05/0.6

P(J|Not B) = 0.0833 = 8.33%

D) This probability is represented by;

P(B | J) = P(B & J)/P(J)

P(B & J) = (P(B) × P(J | B)) = (0.4 × 0.5) = 0.2

P(B | J) = 0.2/0.25

P(B | J) = 0.8 = 80%