1 in 9 or 9% - how to read the steepness of a hill.
Still work in 'old money' but never really understood those signs that said '1 in 9' (9 whatever horizontal = 1 something vertical??). Now we have the % signs. How do these work? What is the difference between 10% and 30%? Which is steeper? 10%/30% of what? Anyone?