a) what is the probability that an applicant for a job at this company's assembly line will be hired?
(0.3 first interview x 0.5 hired) + (0.3 first interview x 0.333 second interview x 0.5 hired) + (0.25 on file x 0.8 interviewed from people on file x 0.25 hired) = 0.25
b) What is the probability that someone who is put "on file" is rejected?
(0.20 rejected) + (0.8 interview x 0.75 rejected) = 0.80
c) what is the probability that someone who is interviewed is hired?
taken right from the original question:
"Of those applicants interviewed, some are rejected immediately, but the probability is 0.50 of being hired immediately"