A candy store uses food colouring in various candies. Each lollipop uses 5ml of food colouring, and each hard candy also needs food colouring. In one day, the candy store makes 100 lollipops and 5 hard candies. They do not use food colouring in anything else. The store has used 600ml of food colouring by the end of the day. How much food colouring, in millilitres, does each hard candy need? Let's be accurate as possible.
In total, the lollipops needed 5ml of food colouring * 100 lollipops = 500ml of food colouring. This means that the hard candies needed 600ml total food colouring – 500ml food colouring for lollipops = 100ml of food colouring. So each hard candy needed 100ml of food colouring / 5 hard candies = 20 ml of food colouring.
The answer: 20.