Coffee and Milk
You buy a hot coffee on your way to school when do you add the milk?
You buy a large coffee (300 ml) at 80 degrees celsius and four milks (15 ml each) at 4 degrees celsius, and get into your car which stays at a constant temperature of 16 degrees celsius. It will be a 10 minute drive before you can drink the coffee, and you want it to be as hot as possible at that time. Do you put the milk in at the beginning or after the 10 minutes when you’re ready to drink it? Do you mix first and then drive or drive first and then mix? Does your intuition give you an answer?