Flooding has washed out one of the tracks of the Snake Gulch Railroad. The railroad has two parallel tracks from Bullsnake to Copperhead, but only one useable track from Copperhead to
Diamondback, as shown in the figure below. Having only one useable track disrupts the
usual schedule. Until it is repaired, the washed-out track will remain unusable. If the train
leaving Bullsnake arrives at Copperhead first, it has to wait until the train leaving
Diamondback arrives at Copperhead.
Bullsnake
Copperhead
Diamondback
Every day at noon a train leaves Bullsnake heading for Diamondback and another leaves
Diamondback heading for Bullsnake.
Assume that the length of time, X, it takes the train leaving Bullsnake to get to Copperhead is
normally distributed with a mean of 170 minutes and a standard deviation of 20 minutes.
Assume that the length of time, Y, it takes the train leaving Diamondback to get to
Copperhead is normally distributed with a mean of 200 minutes and a standard deviation of
10 minutes.
I
These two travel times are independent.