28. A drawn tubing pipeline conveys linseed oil at a rate of 0.0010 m³/s. Determine the optimum economic pipe size for the installation given that: C2 = $0.04/(1 000 W.hr),

t = 7000 hr/yr, a= 1/10 = 0.10, C1= $700/m^n+1, F = 6.75, b = 0.01, n = 1.2, n = 0.75