IMC 2005 Q3
3. Professor Rosseforp has an unusual clock. The clock shows the correct time at noon, but the hands move anti-clockwise rather than clockwise. The clock is very accurate, however, so the hands move at the correct speeds. If you looked in a mirror at the Professor's clock at 1:30 pm, which of the following would you see?
Intermediate Mathematical Challenge 2005, Question 3. © UK Mathematics Trust. Original paper on ukmt.org.uk
Answer: A
As the hands move anticlockwise, at 1:30 pm they would have the appearance they would normally have at 10:30. So, as the clock is viewed in a mirror, it would have the appearance shown in A.
Solution © UK Mathematics Trust, from the IMC 2005 solutions.