Left in previously boiled water for 4 min. We can deduce this from the second sample, which simulates forgetting your tea bag in the mug for 15 min.
replyI think GP meant in the tea instructions
replyIsn't boiled water what goes up into the air?
replyThe boiled water (assuming even heating throughout) is what reaches boiling temperature, 100°C, which is the entire pot. Additional energy applied to the pot/water after that point turns at some rate the already-at-100°C-boiled-water into water vapor/gas/steam. If you stop heating before all the already-at-100°C-boiled-water disappear, you have left what is or will have been "boiled water".
reply