Answer:
a) 83%
b) 0.892
Step-by-step explanation:
percentage that attends class on friday = 74%
percentage that pass because they attend class on friday = 88%
percentage that pass but did not go to school on friday = 20%
a) percentage of students expected to pass the course
 = (74% x 88%) +(88% x 20%)
  = 0.6512 + 0.176
  = 0.8272
  = 83%
b) If a person passes the course, what is the probability that he/she attended classes on Fridays
    = 74% divided by 83%
    = 0.892