Students A, B, and C are discussing a solution of one of homework assignments on Probability and Statistics which was solved by their colleague. Student A will claim, that the solution is wrong if and only if either student B or Student C claims that it is wrong. Students B and C did not have enough time to review the solution, therefore, the student B will say that he found a mistake with probability of 50%. Student C waits a response from the student B, and if the student B claims that he did not find a mistake, student C will claim that he found a mistake with probability of 20%. What is the probability that student B said that he found a mistake, if the student A claimed that the solution is wrong?
I do not uderstend part where highlighted with blue.Can anyone explain? P(B) is wron OR P(C|B') P(B') ... Fro what do we need to multibly by P(B') ?