Seawater containing 3.50wt% salt passes through a series of 10 evaporators. Roughly equal quantities of water are vaporized in each of the 10 units and then condensed and combined to obtain a product stream of fresh water. The brine leaving each evaporator but the 10th is fed to the next evaporator. The brine leaving the 10th evaporator contains 4.70 wt\% salt. What is the weight percent of salt in the outlet from the 3th evaporator? wt\% salt