Four members of Concordia’s Debating Team have been nominated for the office of president of the club. You are interested in joining the debating club (you like to argue with your teachers) but are delaying your decision because of the possible fee hikes. Pundits have established empirical probabilities for the election of the four as follows:

Candidate Probability
Peter 0.3
Christine 0.5
Katherine 0.1
Frances 0.1

Should Peter be elected, the probability for an increase in the membership fees is 0.8. The corresponding probabilities for fee raises upon the election of the other candidates are as follows: Frances (0.1), Katherine (0.4), and Christine (0.5).
What is the probability that Katherine was elected president, given that the fees have been hiked?

a. 67.4%
b. 7.4%
c. 25%
d. 4%
e. 18.51%


please write your calculations

This post was edited by percsssss on Oct 2 2013 12:48pm

look up Bayes' rule

P(katherine|hike) = P(katherine and hike)/P(Hike) = .1*.4/(P(peter and hike)+P(chritine and hike) + P(katherine and hike) + P(Frances and hike)) = .1*.4/(.3*.8+.5*.5+.1*.4+.1*.1) = 7.4%

check the work because I didn't

This post was edited by zackill4 on Oct 2 2013 12:56pm

that was quick. I got it. thanks