Question of the day 19th December 2015

       A certain tank is filled to one quarter of its capacity with a mixture consisting of water and      sodium chloride. The proportion of sodium chloride in the tank is 40% by volume, and the      capacity of the tank is 24 gallons. If the water evaporates from the tank at the rate of 0.5    gallons per hour, and the amount of sodium chloride stays the same, what will be the      concentration of water in the mixture in 2 hours?

      a) 43%               

      b) 50%           

      c) 52%

      d) 54%               

      e) 56%