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 $4.00 a box. the lettuce is sold for $12.00 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 250 boxes with a standard deviation of 31 boxes. how many boxes of lettuce should the supermarket purchase tomorrow? round up the final answer.