Please help me to do this problem in Process Cost Estimation.

Determine the optimum economic pipe diameter for the following conditions. Simplified equations may be used. Assume turbulent flow for the water and viscous/laminar flow for the molasses. Please note that the optimal diameter provided by the relevant equations is in units of metres. Also, the term qf should be in units of m3/s. a) Water at 30C(c=0.0007978Pas,=995kg/m3) with a flowrate of 0.1kg/s. b) Water at 30C(c=0.0007978Pas,=995kg/m3) with a flowrate of 1.5kg/s. c) Water at 30C(c=0.0007978Pas,=995kg/m3) with a flowrate of 10kg/s. d) Molasses at 80C(c=0.0507Pas,=1450kg/m3) with a flowrate of 4.35kg/s