If the operating department sets the unit price for each barrel of water as X yuan (X is rounded to the whole) and the profit is Y yuan, then there will be [480-(X-6) * 40] * (X-5)-200 = Y. Simplify the above formula to get -40*(X-23/2)? 0? The theoretical calculation of 5+ 1490=Y shows that the maximum profit can be obtained when X=23/2. Because x is rounded, when X= 1 1 or 12, the maximum value of y is calculated, and when X= 1 1, Y = 65438. Or when the unit price is 12 yuan, 240 barrels of water can be sold every day, and the maximum profit can be 1480 yuan.