1. A stream containing 10% species A by weight starts to flow at a rate of 2 kg/min into a tank originally holding 300 kg of pure B. a. Simultaneously, a valve at the bottom of the tank is opened and the tank contents are also withdrawn at a rate of 2 kg/min. Considering perfect mixing within the tank, determine the time required for the exit stream to contain 5% species A by weight. b. Consider the problem in part (a). As a result of the malfunctioning of the exit valve, tank contents are withdrawn at a rate of 2.5 kg/min instead of 2 kg/min