On a group trip to a certain city, 20 people who were 25 years old, 20 people who were 30 years old, and 20 people who were 35 years old purchased tickets for the bus tour. no one else purchased tickets for the bus tour. a 30 year old who had purchased a ticket became ill and did not go on the bus tour, and everyone else who purchased a ticket went on the bus tour. which of the following statements is true?