The current market price is based on the first grade of white granulated sugar. Generally speaking, the refined grade is 600-800 yuan more expensive than the first grade, the superior grade is 300-500 yuan more expensive, and the second grade is 20-100 yuan cheaper than the first grade.

Standard deviation, the most expensive minus the cheapest, because the gold grade is 600-800 yuan more expensive than the first level, take the highest value of 800 yuan, the second level is 20-100 yuan cheaper than the first level, take the highest level of 100 yuan, so the standard deviation between the price of white sugar is 900 yuan.