In grading potatoes into small, medium, and large, the Russet Potato Farm packs potatoes that weigh more than 5 ounces in packages marked "large" and the potatoes that weigh less than 2.5 ounces into packages marked "small"; the remainder are packed in packages marked "medium." If a day's packaging contained 10% large and 5% small potatoes, determine the mean and the standard deviation for the potatoes' weights. Assume that the distribution of the weights is normal.