This depends on what material the plumber uses, what fittings the plumber uses, how much piping will be used and how long the plumber will take.
a plumber uses a chisel
depending on the kind of plumber but still not much
It is plumbing or plumber.
You need to be good at math, science. And you have to go to Plumber School. I think there's one in France.
Plumbers
math uses the scientific method
A architect uses math like meausuring length
A teacher mainly uses math to teach it to the students. Other opinions could possibly say that everyone uses math in their life at home as in groceries ect.
plumber
calculator
Population is related to math because it uses percentage