Answer:
60.63%
Explanation:
Prob. of students who regularly attend = 45%
Prob. of students who don't attend = 55%
Upper Class Students who attend = 64 % of 45 %
= 0.64 × 0.45 × 100 = 28.8% = 0.288
Upper Class Students who don't attend = 34 % of 55% = 0.34 × 0.55 × 100 = 18.7% = 0.187
Total for Upper Class Students = 28.8% + 18.7% = 47.5% = 0.475
Probability that an Upper Class Student randomly selected will be attending = ( 0.288 / 0.475 ) × 100 = 0.6063 × 100 = 60.63%