A pressurized propane tank is fitted with a valve on top that allows saturated vapor to escape when the valve is opened. When the valve is first opened, the mass flow rate of the propane leaving the tank is 0.05 kg/s. As the propane vapor escapes, the mass flow rate varies with time according to the following relationship,

where t is in seconds, and a = 0.01 s-1. Determine how long the valve must be open to allow 3 kg of propane vapor to escape from the tank.

m = m, initiale