Question

9. Of 100 individuals who applied for systems analyst positions with a large firm during the past year, 40 had some prior work experience (W), and 30 had a professional certificate (C). However, 20 of the applicants had both work experience and a certificate, and thus are included in both of the counts.

(a) What is the probability that a randomly chosen applicant had either work experience or a certificate ?

(b) What is the probability that a random chosen applicant had either work experience or a certificate but not both?

Answer 1

P(W) = 40/100 = 0.4

P(C) = 30/100 = 0.3

P(W and C) = 20/100 = 0.2

a) P(W or C) = P(W) + P(C) - P(W and C)

                     = 0.4 + 0.3 - 0.2

                     = 0.5

b) P(W or C but not both) = P(W or C) - P(W and C)

                                         = 0.5 - 0.2

                                         = 0.3