Statistics for the Bolandian steam tram system are shown below (figures are for the year 2010):
Total track length: 180km
Number of stops: 48
Individual passenger journeys: 420000
Total tram km: 1.2 million
Total water consumption: 20000 cubic metres
Average time between stops: 8 minutes
Which of the following additional pieces of information would make it possible to calculate the average length of an individual journey?
A The water consumption per passenger kilometre.
B The number of different people using the network in the year.
C The number of trams in service.
D The average speed of a tram.

The answer is A
I would be delighted if you could enlighten me.

To calculate the average length of an individual journey on the Bolandian steam tram system, we need to know the total distance traveled by all the trams and the total number of passenger journeys. We have the total distance traveled by the trams as 1.2 million km, and the number of passenger journeys as 420000. To find the average length of an individual journey, we need to divide the total distance traveled by the number of passenger journeys.

mathematically it can be represented as:
Average journey length = Total distance traveled by trams (1.2 million km) / Number of passenger journeys (420000)

So, the average journey length = 2.857 km (approximately)

However, this calculation only gives us the average distance per journey, but not the energy consumption per passenger km. To find the energy consumption per passenger km, we need to know the amount of water consumed by the trams and divide it by the number of passenger journeys. We have the total water consumption as 20000 cubic meters.

Energy consumption per passenger km = Total water consumption (20000 cubic meters) / Number of passenger journeys (420000)

This gives us the energy consumption per passenger km. By knowing this, we can determine more accurately the average distance per journey, and if the steam tram system is efficient or not.

In summary, A, The water consumption per passenger kilometre is crucial in determining the average length of an individual journey because it provides a measure of energy consumption, which is directly related to the distance traveled. Without this information, it would be difficult to determine the efficiency of the steam tram system and the average journey length.