Answer:
4 minutes.
Step-by-step explanation:
There are three trains that Rachel has to take to go to her job. The total time is taken by her, on average, 1 hour and 20 minutes i.e. (60 + 20) = 80 minutes.
In his journey, she walks for 15 minutes and a train journey for about 53 minutes.
Then the total waiting time for the trains is (80 - 53 - 15) = 12 minutes.
Therefore, the average waiting time, in minutes, at each of the three train stations will be minutes. (Answer)