A volume of 7.2 m3 of glycerol ( = 0.934 Pa s) is pumped through a

Question:

A volume of 7.2 m3 of glycerol (η = 0.934 Pa ∙ s) is pumped through a 15-m length of pipe in 55 minutes. The pressure at the input end of the pipe is 8.6 × 105 Pa, and the pressure at the output end is atmospheric pressure. What is the pipe's radius?