This document discusses probability and uses the birthday problem to calculate the probability of two or more passengers on a flight having the same birthday. It finds that with 20 passengers there is a 41.15% chance of a match, with 30 passengers the chance is 70.63%, and with 40 passengers the chance is 89.12%. It then calculates the expected number of prize awards per month for the airline's promotional contest based on these probabilities. The document demonstrates that the probability of matches is higher than the marketing director's initial assessment and establishes the concept of independent events in probability calculations.