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(7) In an affluent suburb of Cleveland, 45% of the adults identify themselves as

ID: 3361481 • Letter: #

Question

(7) In an affluent suburb of Cleveland, 45% of the adults identify themselves as Republicans, 36% identify themselves as Democrats and the rest are undecided. The local Republican Party office randomly selects adults from that suburb and asks him/her about his/her party affiliation. If somebody is a Republican, the chances of him/her getting an invitation to the 2016 Republican National Convention in Cleveland are 90%. For a Democrat, that probability is 20% and for someone undecided, that probability is 70%. Given that a randomly chosen gentleman from that suburb doesn't get an invitation to the 2016 RNC, what is the conditional probability that he is undecided?

Explanation / Answer

probability that a person does not get an invitation =P(republican and does not get+Democrat and does not get+undecided and does not get) =0.45*(1-0.9)+0.36*(1-0.2)+(1-0.45-0.36)*(1-0.7) =0.39

therefore probability that gentlemen is undecided given not received invitation

=P(undecided and does not get)/P(not reeived invitation)=(1-0.45-0.36)*(1-0.7)/0.39 =0.1462