Lettuce each day to ensure really fresh produce

The local supermarket buys lettuce each day to ensure really fresh produce. Each morning any lettuce that is left from the previous day is sold to a dealer that resells it to farmers who use it to feed their animals. This week the supermarket can buy fresh lettuce for $9.00 a box. The lettuce is sold for $20.00 a box and the dealer that sells old lettuce is willing to pay $2.50 a box. Past history says that tomorrow's demand for lettuce averages 260 boxes with a standard deviation of 41 boxes.