In a certain school, 4 levels of French are taught with 40% of the students being enrolled in level 1, 30% enrolled in level 2, 20% enrolled in level 3, and 10% enrolled in level 4. The percentage of people who enjoy their French class is 70% in level 1, 80% in level 2, 85% in level 3, and 90% in level 4.
Given that a person enjoys his/her French class, let pj be the probability that the student is enrolled in level j. Find pj for j = 1,2,3,4. (Check: Your four answers should sum to 1 altogether.)