Philosopher Watch Problem

One absentminded ancient philosopher forgot to wind up his only clock in the house. He had no radio, TV, telephone, internet, or any other means for telling time. So he traveled on foot to his friend's place few miles down the straight desert road. He stayed at his friend's house for the night and when he came back home, he knew how to set his clock. How did he know?

For Solution: Click Here


  1. Very simply...
    1) He winds his clock, let's say it shows 7:00
    2) He walks to his friend's house and looks at the clock... let's say it says 5:15
    3) Now he stays for awhile, let's say until 8:15 in the morning (15 hours later).
    4) He goes home and looks at his clock. He would expect it to say 10:00 (15 hours later), but instead he will see a time like 10:20. He then knows the trip to and from his friend's house takes 20 minutes (10 minutes one way).
    5) He sets his clock to 8:25 (8:15 + 10 minutes walking) and his clock is now correct.

  2. He borrowed a watch from his friend?

    1. That's what I thought!! :D

  3. He took his clock with him to his friends house.