hardlogic

Illustration for riddle: My only timepiece is a wall clock. One day I forgot to wind it and it stopped. I went to visit a fri — Can you figure out this riddle?

My only timepiece is a wall clock. One day I forgot to wind it and it stopped. I went to visit a friend who has a watch which is always correct, stayed a while, and then went home. There I made a simple calculation and set the clock right. How did I do this even though I had no watch on me to tell how long it took me to return from my friend's house?

Before I left, I wound the wall clock. When I returned, the change in time equaled how long it took to go to my friends house and return, plus the time I spent there. But I knew the latter because I looked at my friends watch when I arrived and left. Subtracting the time of the visit from the time I was absent from my house, and dividing by 2, I obtained the time it took me to return home. I added this time to what my friend watch showed when I left, and set the sum on my wall clock.

Why this works

This riddle plays with the concept of time measurement and utilizes logical reasoning to arrive at the solution. The key is that although the wall clock had stopped, the person wound it before leaving, so it was set to the correct time at that moment. When they visited their friend, they noted the time displayed on the friend's always-correct watch both upon arrival and departure, allowing them to calculate the duration of their visit. Upon returning, they used the total elapsed time (the time they were away from home) and subtracted their visit's duration to find out how long it took to travel to and from their friend's house. By halving that time and adding it to the time on their friend's watch when they left, they could accurately set their wall clock, demonstrating a clever use of subtraction and division to track time without needing a watch themselves for the whole journey.

Common Wrong Answers

“I used my phone to check the time when I left and returned.”

The riddle states that the person did not have a watch on them when they returned home, which implies they also did not have access to a phone or any other timing device.

“I remembered the exact time I left and calculated how long it took based on my memory.”

Relying on memory alone is not reliable enough to accurately determine the time taken for the entire trip, especially without a time reference upon return.

“I guessed the time it took me to return and set the clock based on my intuition.”

Guessing would not provide an accurate method to set the clock correctly, as the riddle involves a logical calculation based on observed time rather than intuition.

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