For a chance to win the first prize (£100 Amazon voucher), or one of our prizes for runners-up, submit your typed or neatly written solutions of the following problems tomaths@lincoln.ac.ukor by post to Mathematics Challenge, School of Mathematics and Physics, University of Lincoln, Lincoln, LN6 7TS. Please include your full name, postal address and email, as well as the name and address of your school. The closing date is 5 January, 2017. The competition is open to all young pre-university people in UK aged 16–18 years. It is not open to current university students. See full Terms and Conditions. The problems can also be downloaded from here.

1. Suppose that alloy A contains 40% gold by weight, and alloy B contains 25% gold. How much of each of these alloys should be taken to be melted together so as to produce 600 grams of alloy containing…