Question

An overpass 250 metres long is to be constructed using reinforced concrete with weight per metre given by W = 50.S+500, in which S is the span between piers in metres. The piers will cost $500,000 each, and the superstructure can be erected at cost of $500 per tonne. Assuming there is no limit to the weight that can be carried by each pier, calculate the number of piers that minimises the total cost of the overpass.

Answer 1