sentence1: If the next three flights departed on - time , how many subsequent flights need to depart from Phoenix on - time , for the airport ' s on - time departure rate to be higher than more than 20 % ? I will see what is the quickest way to solve it then I will provide the explanation
sentence2: If the next three flights departed on - time , how many subsequent flights need to depart from Phoenix on - time , for the airport ' s on - time departure rate to be higher than 80 % ?
  I will see what is the quickest way to solve it then I will provide the explanation