Project Management Homework help

On May 21, 1921, Charles Lindbergh landed at Le Bourget Field in Paris, completing his famous transatlantic solo flight.  The preparation period prior to his flight was quite hectic and time was critical, since several other famous pilots of the day were also planning transatlantic flights.  Once Ryan Aircraft was contracted to build the Spirit of St. Louis, it took only a little over 2 ½ months to construct the plane and fly it to New York for the takeoff.  If CPM/PERT had been available to Charles Lindbergh, it no doubt would have been useful in helping him plan this project.  Use your imagination and assume that a CPM/PERT network, as shown in the figure below, with the following estimated activity times, was developed for the flight. 

Assignment:  Determine the expected project duration and variance and the probability of completing the project in 67 days.