Mathematics

# The weight W kg of a metal bar varies jointly as its length L meters…

The weight W kg of a metal bar varies jointly as its length L meters and the square of its diameter d meters. If w = 140 when d = 42/3 and L = 54, find d in terms of W and L.
• A.
(sqrt{frac{42W}{5L}})
• B.
(sqrt{frac{6L}{42W}})
• C.
(frac{42W}{5L})
• D.
(frac{5L}{42W})