The haze weather is becoming more serious in the central and eastern regions of my country, and environmental governance has become urgent. According to public health measures, an electrical appliance mall in our city

Solution: (1) According to the question: y=-5x+2200.

(2) According to the meaning of the question:

The solution is 300≤x≤350.

(3) From (1): w＝(-5x＋2200)(x-200)

＝-5x2＋3200x-440000＝-5(x-320)2＋72000． ∵x=320 within 300≤x≤350, ∴When x=320, w is maximum=72000.

That is, when the selling price is set at 320 yuan/unit, the maximum profit that can be obtained is 72,000 yuan.