There are some doubts about this: Dongting Lake, a famous freshwater lake in China, has been silted up due to soil erosion and other reasons, and its area has been reduced from about 4,350 square kilometers to 2,700 square kilometers, and the lake area of Dongting Lake has been reduced by several percent. Ordinary students' thinking: this question actually seeks the percentage of the reduced area to the original area. First calculate the reduced area: 4350-2700= 1650 (square centimeter), and then calculate the percentage from 1650 to 4350 by division.
The strategy of underachievers: First, calculate how many square kilometers the existing area is less than the original area. According to the quantitative relationship "original area-present area = less area", the formula is 4350-2700= 1650 (square centimeter). Then calculate the percentage of the reduced area to the original area, divide the score by the unit "1" in the question, and the unit "1" in the question is the original area, that is, the reduced area ÷ the original area, and the formula is: 1650÷4350.
Answer: Ordinary students: (4350-2700) ÷ 4350 ≈ 37.9%; Underachievers: 4350-2700= 1650 (square centimeter) 1650÷4350≈37.9% A: The area of Dongting Lake decreased by 37.9%.