Jane has to bake a cake for her friends who are about to arrive. Her electric clock stopped working because of a power outage so she’s using her gas oven. She had already begun baking the cake and needed to keep it in the oven for 17 more minutes when the power went out. If the cake stays in the oven any longer, it will burn.
Jane has two hourglasses to keep an eye on the time right now. One runs for 7 minutes, and the other for 11 minutes.
Jane soon worked out how to track time using these two hourglasses. She took the cake out of the oven after 17 minutes, and it turned out baked perfectly because she timed it just right.
Can you figure out how Jane managed to track her time with the help of hourglasses?
——— View the answer ———
To bake a cake for 17 minutes, follow these four steps.
- Continue baking the cake and flip both hourglasses at the same time.
- When the 7-minute hourglass empties, flip it over to start it again.
- When the 11-minute hourglass empties, flip it once more.
- Let the 7-minute hourglass run out again. At the same time flip the 11-minute hourglass again and when it empties after 3 minutes, it will be exactly at the 17 minute mark.
