A train travels a certain journey and is supposed to arrive at midday. When I s average speed is 40km/h, it arrives at 1 p.m. When its average speed is 48km/h it arrives at 11a.m. What is the length of the journey
Let's assume the length of the journey is L km.
When the train's average speed is 40 km/h, it takes 1 hour longer to complete the journey. So, the time it takes to complete the journey is L/40 hours.
When the train's average speed is 48 km/h, it takes 1 hour less to complete the journey. So, the time it takes to complete the journey is L/48 hours.
From the given information, we can write two equations:
L/40 = 1 (since it arrives at 1 p.m.)
L/48 = -1 (since it arrives at 11 a.m.)
Simplifying the equations, we get:
L = 40 (since L/40 = 1)
L = -48 (since L/48 = -1)
Since the length of a journey can't be negative, we discard L = -48 as an extraneous solution.
Therefore, the length of the journey is L = 40 km.