A 220 yard long train, travelling at 90 mph, enters a tunnel of 3 miles in length.

How long will elapse from the moment the front of the train enters the tunnel till the moment the end of the train clears the tunnel?

For a chance to win one of two Mensa Brain Trainer hand held consoles, simply e-mail the correct answer together with your full name and address to the Puzzle Editor or please email: puzzles@mensa.org.uk

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Closing date is 31 December 2011.

The first two correct entries selected will be declared the winners and will be notified by the competition judges. The judge's decision is final; no correspondence will be entered into. Congratulations to last month's winners: M Lycett, Walsall and D Sharpe, Rutland. The correct answer was: 9.