The first flight out of Phoenix airport had a late departure

The first flight out of Phoenix airport had a late departure. 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 40%? I will see what is the quickest way to solve it then I will provide the explanation

AQuA-RAT — Algebra Question Answering with Rationales (Ling et al., DeepMind, 2017) · train #41674