A large company normally recruits 20 accountancy trainees per annum. In 1978, 90 applicants were received and of these

63 had previous work experience

36 had passed the foundation stage examination

27 had both work experience and had passed the foundation stage examination, and had been included in both the above counts.

a) Given that the applicant must have work experience, determine the conditional probability that an applicant taken at random from this group will have passed the foundation stage examination.