A 3-ft-diameter duct is used to carry ventilating air into a vehicular tunnel at a rate of \(9000 \mathrm{ft}^{3} / \mathrm{min}\). Tests show that the pressure drop is \(1.5 \mathrm{in}\). of water per \(1500 \mathrm{ft}\) of duct. What is the value of the friction factor for this duct and the approximate size of the equivalent roughness of the surface of the duct?