The bar graph shows the numbers of hours you volunteered at the local Children's Hospital. What is the minimum number of hours you need to volunteer in the seventh week to justify that you volunteered an average of 10 hours per week for the 7 weeks? Explain your answer using measures of center.

A bar graph titled Volunteering at the Children's Hospital. The y-axis labeled Hours goes from 0 to 18 in increments of 2. The x-axis labeled Week. The Week 1 bar goes to 6. The week 2 bar goes to 15. The week 3 bar goes to 11. The week 4 bar goes to 7. The week 5 bar goes to 10. The week 6 bar goes to 9.