EXERCISE 10.8 · Part 2

placed it on a nearby Kitchen counter to cool. At this instant the temperature of the coffee was  F , and minutes later it was  F . Assume that constant temperature of the kitchen was  F . (i) What was the temperature of the coffee at .15A.M.? log =−     (ii) The woman likes to drink coffee when its temperature is between  F and  F . between what times should she have drunk the coffee? . A pot of boiling water at  C is removed from a stove at time t = and left to cool in the kitchen. After minutes, the water temperature has decreased to  C , and another minutes later it has dropped to  C . Determine the temperature of the kitchen. , log =−     =−     - - Ordinary Differential Equations . A tank initially contains litres of pure water. Starting at time t = a brine containing with grams of dissolved salt per litre flows into the tank at the rate of litres per minute. The mixture is kept uniform by stirring and the well-stirred mixture simultaneously flows out of the tank at the same rate. Find the amount of salt present in the tank at any time t > .