Mrs Amanda Evans kindly agrees to help raise money for the new school by operating a cake stall at the local fete. She bakes a number of delicious cupcakes which all weigh the same. The fete organisers insist that Mrs Evans declare the weight of the cakes to potential customers.
This is problematic as the only scales she owns has one arm longer than the other. When she places 16 cakes in the left bowl and a 1kg weight in the right bowl, the scales are evenly balanced. They are also evenly balanced when she places 4 cakes in the right bowl and the 1 kg weight in the left bowl. How much does one cake weigh?
You can find the answer here.