Averages: mean, median and mode. When in school, you use them to determine your grade. Sports fans understand them with batting averages, yardage per game, etc... What about how averages apply to working a job and making money, something most students can grasp?
If your income is commission-based, you can determine your average pay per week, month or year. If you have a business, you can use averages to determine what and when products and services sell the best. You can average your expenditures (food, housing, gas) to help create and stick to a budget.
Averages go beyond adding all the numbers and dividing by the number of numbers. How else can you apply it?