A large city’s transit department claims that only 10% of city buses run off schedule. To test this claim, a random sample of 10 buses is chosen at random. Five of the buses are running off schedule. To see how unusual this sample of buses is, a simulation of 100 trials was conducted under the assumption that 10% of the buses run off schedule.
Answer: There is about a 3% chance that 5 or more buses are running off schedule. This is unusual and is convincing evidence that the true probability that a bus is off schedule is more than 10%