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# Did You Find Out? Get the Answer to the Riddle of E-News Issue No. 1, February 2020

2020-02-05

## Favorite Meal

How can Emma guarantee the cooking time with the two hourglasses?

Emma wants to cook her husband Erwin his favorite meal, spaghetti bolognese. In addition to the delicious sauce, the consistency of the pasta is especially important. It should not be too hard, too soft, or too sticky, but "al dente", or firm when bitten. This means the noodles have to cook for exactly 11 minutes. Emma notices that her kitchen clock is broken, and only two hourglasses are on the kitchen shelf. One runs for 5 minutes and the other for 8 minutes.

How can Emma guarantee the 11-minute cooking time?

## Solution

There are two solutions for this task:

1. When the water is boiling, Emma turns both hourglasses over at the same time. After 5 minutes, the first hourglass finishes running. Now, she pours the noodles into the water. 3 minutes later, the 8-minute hourglass also stops, and Emma immediately turns it over again. When this hourglass has finished running for the second time, a total of 11 minutes will have passed since the noodles were added to the water.

2. Emma puts the noodles directly into the pot as soon as the water starts to boil and turns over both hourglasses simultaneously. After 5 minutes, the first hourglass is immediately turned over and continues to run. After 8 minutes, when the second hourglass has finished running, she turns the 5-minute hourglass over again so that the remaining 3 minutes can run out. This way, the noodles cook for a total of 11 minutes.

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