II. JOINT VARIATION Solve the following problem. The weight (W) of a cylindrical metal varies jointly as its length (l) and the square of the diameter (d) of its base. a. If W = 6 kg when l = 6 cm and d = 3 cm, solve for k then find the equation of variation. b. Find I when W = 10 kg and d = 2 cm. c. Find W when d = 6 cm and l = 1.4 cm