If you expected Old Faithful to erupt every hour, you would expect to wait a total of 60 * k minutes to see k eruptions. Set difference_from_expected to an array with 272 elements, where the element at index i is the absolute difference between the expected and actual total amount of waiting time to see the first i+1 eruptions. Hint: You'll need to compare a cumulative sum to a range. For example, since the first three waiting times are 79, 54, and 74, the total waiting time for 3 eruptions is 79 + 54 + 74 + 207. The expected waiting time for 3 eruptions is 60' 3 = 180. Therefore, difference-from expected. item (2) should be 1207 - 1801 = 27.