Proportionality calculations lead to the use of the so-called 'rule of 3', also nammed the 'cross product law'.
Let's study it with an example.
If it lasts 15 minutes to bake 500 g of rastbeef, how much time shalll I bake my 950 g rastbeef?
Let's call x the time in minutes that we are looking for.
Then the time per gram is either 15 min over 500 g, or x min over 950 g:
------ = ------ (1)
If we multiply...