Journal of the Mathematics Council of the Alberta Teachers’ Association
Volume 4 Issue 3, June 1965
8
Editors W. F. Coulson and T. P. Atkinson
The time is between 5 and 6 p.m. In 15 minutes it will be as many minutes before 7 p. m. as it was past 5 p. m. 9 minutes ago. What time is it now?
A coin collector has a set of nine coins identical in appearance but he knows that one is counterfeit and weighs slightly more than one of the genuine coins, which all weigh the same. The man has a scale balance and in two weighings is able to identify the counterfeit coin. How does he do it?
