A bus travels between two cities, but visits six intermediate cities upon the route. The means and standard deviations of the travel times are as follows:
City Pairs Mean Time (hrs) Standard Deviation (hrs)
1-2 5 1.2
2-3 3 0.4
3-4 4 0.3
4-5 6 0.5
5-6 4 0.6
6-7 5 0.4
7-8 7 0.9
(a) What is the probability that the bus completes its journey within 36 hours?
(b) What is the probability that the bus takes greater than 40 hours to complete its journey?
(c) What is the probability that the bus takes less than 32 hours to complete its journey?