A 1:200 (V/V) solution of isoproterenol would be given by ratio solutions. The ratio solutions represent the relation of a part of a solute and the parts of a solution. For example, 1:200 solution of isoproterenol represents the relation of a part of a isproterenol which is the solute and the parts of the solution. So, to make this solution, we need 1 ml of solute - isoproterenol in 200 ml of solution.
