GilliganBoatworkshas received more warranty claims this year associated with cracking in the exterior finish of the hull. Gel coat that is too thin negatively affects the finish over the life of the boat because of exposure to salt water and sunlight, so Gilligan wants to start his failureanalysis with gel coat.He gets his production supervisor to collect data about the gel coat process and it is determined that the average thickness of the coating is 15mm with a standard deviation of 2.5mm. In order to ensure that no more than 2.5% of the hulls are "too thin" what is the minimum thickness of the gel coat?