13. A carpenter will be using 24″ × 3/8″ handsplit cedar shakes to cover a roof. The shakes will be applied with an average spacing of 1/2″ between shakes, and the weather exposure will be 71/2″. Based on the shake coverage table, if the total roof area to be covered is 768 square feet, how many squares of the shakes will be needed to cover the roof? (Round your answer up to the nearest whole square.)
A. 11
B. 10
C. 12
D. 14