At the same time two planes depart from JFK international airport. One plane flies exactly in northern direction, while the other one flies exactly to the east. Both planes fly at the same speed and at the same height. Which plane is after one hour the most far away from JFK?

How should you saw a block of stone of 40 kg into four pieces such that you can measure all weights of an integer from 1 kg to 40 kg (so 1 kg, 2 kg, 3 kg, 4 kg, ..... 39 kg and 40 kg) on a balance?

A soccer team just became first in the national league. The players which were on the field just after the referee blew the final signal wanted to congratulate each other by shaking hands. Assuming that each player shook hands with every other player only once, how many time were the hands shaken in total? (There are of course 11 players in a soccer team)