Station send buses outon reg intervals,first 4 depart times is 9:15am 9:53am 10:31am 11.09am earliest dan can get bus if he cant leve til 2.15am =? Solution This is clearly an arithmetic progression. There is the same interval between each of the times that the buses leave the station. Therefore, all you have to do is keep adding that interval to the previous departure time until you get past 2:15. I assume you mean 2:15 PM, not AM... So, the interval between each of these departure times is 38 minutes. The last departure time was 11:09. 38 minutes after that is 11:47. Then 12:25. Then 1:03. Then 1:38. Then 2:13. Since Dan can\'t leave on that one, he has to wait until 2:48 for the first bus that he can take..