1. The subway is accelerated on the first 423 m and must be decelerated on the following 423 m.
According to you'll get
According to the maximum speed of the train is
(Did I mention that the driver is mad?)
2. According to the results at 1. the train needs 44,1 s from one station to the next.
3. With a 22 s stop at the station the elapsed time from one stop to the next is 66 s, the total distance is 846 m, thus the average speed is: