Solve the Problem $\mathrm { S }$ Of a Rectangular Wooden Beam Is Proportional to Its Width

Solve the problem.
-The strength $\mathrm { S }$ of a rectangular wooden beam is proportional to its width times the square of its depth. Find the dimensions of the strongest beam that can be cut from a 10 -in.-diameter cylindrical log. (Round answers to the nearest tenth.)

A) w = 5.8 in.; d = 8.2 in.
B) w = 6.8 in.; d = 7.2 in.
C) w = 6.8 in.; d = 9.2 in.
D) w = 4.8 in.; d = 9.2 in.