What should be the value of the fourth column?

                                                    55                      83                        45                        ?

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

Curious About Your IQ?

Train Your Brain?

Closing date is 31 January 2012.

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: J Rhead from Stroud and R Brooksbank from Derby. The correct answer was: 2 minutes, 5 seconds.