Brain Teaser #26
Bob was paddling his canoe upstream at a constant rate. After 6 miles, the wind blew his hat into the stream. Thinking he had no chance to recover his hat, he continued upstream for 6 more miles before turning back. He continued rowing at the same rate on his return trip and overtook his hat at exactly the same spot where he began his journey 8 hours earlier. What was the velocity of the stream?