We are given that 80% of scheduled flights really take place, therefore this means that:
Probability of flying = 80% = 0.80
Now in statistics class, we know that the probability of two or more independent events to occur is simply equivalent to the product of their probabilities, or mathematically written as: (P = Probability)
total P = P1 * P2 * P3 *...
In this case, since we are to find for the probability that 3 independent flights will occur, therefore the total probability assuming equal probabilities to fly is:
total probability = 0.80 * 0.80* 0.80
total probability = 0.512
or
total probability = 51.20%
This means that there is only a 51.20% chance for 3 flights to occur.