Answer:
0.55 or 11/20
Explanation:
The bus is either on time, early, or late. Since the probability the bus is early is 0.15, and the probability the bus is on time is 3/10, or 0.3, the probability the bus is late is just 1 - probability on time - probability early, since all three probabilities must add to 1.
Therefore, 1 - 0.3 - 0.15 = 0.55 = 11/20.