The Surf-excel company uses a machine to fill boxes with soap powder. Assume that the net weight of the boxes of soap is normally distributed with mean 15 ounces and standard deviation 0.8 ounces. 25%...

The Surf-excel company uses a machine to fill boxes with soap powder. Assume that the net weight of the boxes of soap is normally distributed with mean 15 ounces and standard deviation 0.8 ounces. 25% of the boxes will be heavier than a certain net weight ? and 75% of the boxes will be lighter than this net weight. Find ? .