7. The durations of a set of activities are as follows: aj : [0,5), az : [1, 9), az : [4,6), a4 : [6, 11), a5 : [7, 12), 26 : [8, 13) Note the notation here, which is standard in mathematics. The square bracket at the beginning of an interval indicates that the beginning time is included in the interval, while the parenthesis at the end indicates that the endpoint is not included... So it is okay to schedule both [4,6) and (6,11) for example. The maximum number of activities that can be scheduled is: 1 2 3 4