2010 AMC 10A Problem 1

Mary’s top book shelf holds five books with the following widths, in centimeters: 6, \dfrac{1}{2} , 1, 2.5, and 10. What is the average book width, in centimeters?

\mathrm{(A)}\ 1 \qquad \mathrm{(B)}\ 2 \qquad \mathrm{(C)}\ 3 \qquad \mathrm{(D)}\ 4 \qquad \mathrm{(E)}\ 5

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.