##### Question 4.2.6
1. There is a story about Archimedes that says a king asked him to work out if a crown was pure gold, or a mix of gold and silver. Archimedes found out by measuring the mass and volume of the crown. Gold weighs $20$ grams for every millilitre, and silver weighs $10$ grams for every millilitre. If the crown weighed $250$ grams, and its volume was $15$ millilitres, was it pure gold? Show answer

2. Guess how many millilitres of gold and how many of silver went into the crown, and see if you are right. (This question is answered with algebra in Question 7.5.36.) Show hint