You could ask: "Three quarters" of the way from WHAT temperature to boiling?
It sounds like the grandparent is trying to measure how far through the task of boiling their water is, by interpreting degrees Celsius as percentage done.
Maybe they usually make soup or tea by boiling ice cubes. (Perhaps they're Siberian?)
Are they saying that 75 degrees mean three quarters of the way from room temperature tap water to boiling water? Or are they talking about boiling an ice cube, so it's three quarters from 0 Celsius freezing?
Interpreting degrees Celsius as a percentages is not an intuitive way of measuring time elapsed to boil tap water, because 75% between freezing and boiling doesn't mean 75% of the time required to boil has elapsed, since you're starting from room temperature when you boil tap water, not freezing.
Comments
You could ask: "Three quarters" of the way from WHAT temperature to boiling?
It sounds like the grandparent is trying to measure how far through the task of boiling their water is, by interpreting degrees Celsius as percentage done.
Maybe they usually make soup or tea by boiling ice cubes. (Perhaps they're Siberian?)
Are they saying that 75 degrees mean three quarters of the way from room temperature tap water to boiling water? Or are they talking about boiling an ice cube, so it's three quarters from 0 Celsius freezing?
Interpreting degrees Celsius as a percentages is not an intuitive way of measuring time elapsed to boil tap water, because 75% between freezing and boiling doesn't mean 75% of the time required to boil has elapsed, since you're starting from room temperature when you boil tap water, not freezing.