Theresa’s parents have agreed to buy her tickets to see her favorite band if she spends an average of 10 hours per week helping around the house for 6 weeks. For the first 5 weeks she helps around the house for 8,11,7,12 and 10 hours. How many hours must she work during the final week to earn the tickets?
Answer Choices
A. 9
B. 10
C. 11
D. 12
E. 13