"ANSWER: 600

All of the numbers are times (11:00, 11:20, 12:00, etc). To determine what time comes next you add multiples of 20 minutes in increasing order. In other words, to get from 11:00 to 11:20 you must add 20 minutes. Then you add 40 minutes to 11:20 to get 12:00. If you continue to do this, 6:00 would come after 4:00 since 120 minutes would need to be added. Therefore, the answer is 600."

Winner: Michele in Illinois

Contest Statistics: Newsletter sent to 313891 subscribers, 14 answers submitted, 12 answers correct, 85.71% accuracy. Chance of a correct answer winning: 8.33%. The only 2 incorrect answers were the same: 300.