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Boat scenes

PLEASURE boats ply in each direction along the canal from Eastbridge to Westford and back. They leave each place on the hour and every 15 minutes.

One day I left Eastbridge to walk along the towpath to Westford. I left at 12 o’clock and arrived at Westford at the same time as the boat that had left Eastbridge at 12.15. On my walk I saw eight boats going in the opposite direction, including one which arrived at Eastbridge as I left, and one which left Westford as I arrived.

The next day I left Eastbridge to cycle along the towpath to Westford at 6 kilometres per hour faster than I walked. Again, I left at 12 o’clock but this time I arrived at Westford at the same time as the boat which had left Eastbridge at 11.45. On my walk I saw six boats going in the opposite direction, including one which arrived at Eastbridge as I left, and one which left Westford as I arrived.

What is the speed of the boats?

£15 will be awarded to the sender of the first correct answer opened on Friday 19 December. The Editor’s decision is final. Please send entries to Enigma 1521, New ÐÓ°ÉÔ­´´, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address). The winner of Enigma 1515 is Loren Austin of Sheffield, UK.

Answer to 1515 Relative sizes

BEETLES is 4335036