A large tank is filled with methane gas at a concentration of 0.585 kg/m3 The valve of a 1.38-m pipe connecting the tank to the atmosphere is inadvertently left open for fourteen hours. During this time, 9.35 10-4 kg of methane diffuses out of the tank, leaving the concentration of methane in the tank essentially unchanged. The diffusion constant for methane in air is 1.97 10-5 m2/s. What is the cross-sectional area of the pipe? Assume that the concentration of methane in the atmosphere is zero.