In total, the lollipops needed 5ml of food colouring * 100 lollipops = <<5*100=500>>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 = <<100/5=20>>20 ml of food colouring.
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