In a group of 294 students, 130 are seniors and 121 are males. Exactly one-half of seniors are females. If a student is randomly selected, what is the probability that the student is a senior or a female?

1 Answer
Jun 4, 2017

P("senior"uu"female")=16648/21609

Explanation:

Because 121 students are male, 294-121=173 students are females

P("senior"uu"female")=P("senior")+P("female")-P("senior"nn"female")
Because being a senior and being female are two independent events, therefore P("senior"nn"female")=P("senior")*P("female")

i.e.P("senior"uu"female")=P("senior")+P("female")-P("senior")*P("female")

P("senior"uu"female")=130/294+173/294-130/294(173/294)=16648/21609