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Rule of Three
If it takes four men one day to build a wall, how long does it take 60,000 men to build a similar wall?
Crossing the Atlantic
Every day at noon a boat leaves Le Havre for New York while another boat leaves New York for Le Havre. The ocean crossing takes seven days. How many boats will each boat cross during their journey?
On Time
On a clock the three hands - the second, minute and hour hands - are on the same axis. How often in a 24 hour day will the second hand be parallel to either of the two other hands?
Age 11 to 14 Short
Challenge Level
An athlete covers three consecutive miles by walking the first mile, running the second mile and cycling the third. He runs twice as fast as he walks, and he cycles one and a half times as fast as he runs. He takes ten minutes longer than he would do if he cycled the three miles. How long does he take by walking, running and cycling?
If you liked this problem, here is an NRICH task that challenges you to use similar mathematical ideas.
NRICH is part of the family of activities in the Millennium Mathematics Project.