Question 11
To make Bibimbap, four ingredients are prepared separately and mixed at the end. Their required stages and durations are shown.
English translation: greens boil in the pot for 10 minutes, then are chopped for 5; bean sprouts soak in the bowl for 5, then boil in the pot for 10; carrots are chopped for 5, then stir-fried in the pan for 10; eggs fry in the pan for 5. The kitchen has only one pan, one pot, one knife-and-board set and one bowl, but work on different tools can overlap. For example, greens can boil for 10 minutes while eggs fry for 5. What is the shortest time to finish preparing all four ingredients?
English translation: greens boil in the pot for 10 minutes, then are chopped for 5; bean sprouts soak in the bowl for 5, then boil in the pot for 10; carrots are chopped for 5, then stir-fried in the pan for 10; eggs fry in the pan for 5. The kitchen has only one pan, one pot, one knife-and-board set and one bowl, but work on different tools can overlap. For example, greens can boil for 10 minutes while eggs fry for 5. What is the shortest time to finish preparing all four ingredients?