Abdulla wants to decide on the best route to take for work from two possible routes: A and B. The time taken to work on each route depends on the traffic. If Abdulla takes route A, it will take him 25 minutes if the traffic is moderate and 45 minutes if the traffic is high. If Abdulla takes route B, it will take him 15 minutes if the traffic is moderate and 55 minutes if the traffic is high. Assume that on a particular day, the probability of moderate traffic is 40% and the probability of high traffic is 60%.

a) Construct a decision tree for the problem.

b) Determine the best route to take using the expected value criterion.