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The total mass of five rugby players is $425 \; \text{kg}$ and the average (mean) mass of ten ballet dancers is $40 \; \text{kg}$. What is the average mass of all fifteen people?

If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.

*This problem is taken from the UKMT Mathematical Challenges.**View the archive of all weekly problems grouped by curriculum topic*