I need help with this (the values are incorrect)

Coleman Rich Control Devices, Inc., produces custom-built relay devices for auto makers. The most recent project undertaken by Rich requires 14 different activities. Rich's managers would like to determine the total project completion time (in days) and those activities that lie along the critical path. The appropriate data are shown in the following table: Time (days) Immediate Predecessor(s) Activity H a m 3 1 Activity B D E F G Time (days) a m b 5 7 9 1 2 4 5 5 5 6 10 11 3 8 18 1 3 6 2 7 8 A B, C D D J K L M N 1 7 3 1 7 3 5 5 10 4 2 7 b 7 8 8 12 8 4 10 Immediate Predecessor(s) E, F G H 1 1 J K LM a) The expected completion time of the project = 51.67 days (round your response to two decimal places). The activities that represent the project's critical path are A-C-E-H-I-K-M-N. b) If the time to complete the activities on the critical path is normally distributed, then the probability that the critical path will be finished in 53 days or less = 0.66 (round your response to two decimal places). c) Number of days that would result in 99% probability of completion = 59.38 days (round your response to two decimal places)