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Julie Myers, a graduating senior in accounting, is preparing for an interview wi

ID: 2684105 • Letter: J

Question

Julie Myers, a graduating senior in accounting, is preparing for an interview witha Big eight accounting firm. Before the interview, she sets her chances of eventually getting an offer at 50%. Then, on thinking about her friends who have interviewed and gotten offers from this firm, she realizes that of the people who recieve offers, 95% had good interviews. On the other hand, of those who did not receive offers, 75% said they had good interviews. If Julie Myers hasa good interview, what are her chances of receiving an offer ?

Explanation / Answer


Pr(Offer) = 0.50,

Pr(Good Interview| Offer) = 0.95, Pr(Good Interview| No Offer) = 0.75

-- Apply Law of Total Probability

Pr( Good Interview) = Pr( Good Interview | Offer)Pr(Offer) +Pr( Good Interview | No Offer)Pr(No Offer)

Pr(Good Interview) = 0.95 0.50 + 0.75 0.50

= 0.85

-- Apply calculation rule for conditional probability

Pr( Offer | Good Interview) = [Pr( Good Interview | Offer)Pr(Offer)] / [ Pr(Good Interview)]

Pr( Offer | Good Interview) = 0.95 * 0.50/0.85

= 0.559

Only a slight increase is observed in our beliefs in getting an offer after we had a good job interview (from 0.500 to 0.559). The reason is that the people’s judgement regarding “Good Interviews” is not very informative. Indeed,

Pr(Good Interview| Offer) = 0.95

Pr(Good Interview| No Offer) = 0.75.