The question asks for the number of cars passing through a certain day. It provides the following assumptions:
Length of the bridge= 10 km
Car length = 3 m
Spaces between cars = 2 m
Given this, I would assume that the upper limit for the number of cars at any moment will be 10 km / (5m).
How would I take into account the replacmenet concept ? so how can I actually calculate the rate at which the cars enter the bridge (per hour).