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Mathematics problem: super difficult! Please help! Urgent! Urgent! Urgent! A cuboid is 5cm in length and 3cm in width. If it is rotated around the length of the rectangle, a cylinder will be obtained. What is the surface area of the cylinder? If it is rotated around the width of the rectangle, a cylinder will also be obtained. What is the volume of the cylinder? (formula calculation)
3.14x5x5x2 + 3.14x5x2x3 = 251.2 square centimeter
3.14x3x5 = 141.3cm
After Master Wang processed 1500 parts, he improved the technology and increased the work efficiency to 2.5 times of the original. When he later processed another 1500 parts, it took 18 hours less than before. How many parts per hour before and after the improvement? (solved by equation and arithmetic)
(1) Suppose x pieces are processed per hour before the improvement of the technology, then 2.5x pieces are processed per hour after the improvement of the technology
How many different cylinders can be obtained by rotating a 6cm long and 4cm wide rectangle around one side of it? What are their volumes (π is retained as a result)?
Two different kinds of cylinders can be obtained as follows:
The diameter of the cylinder is 4cm and the height is 6cm if the side of 6cm is rotated. This can be calculated
Volume = bottom area * height = 3.14 * 2 ^ 2 * 6 = 75.36cm ^ 2
If the edge of 4cm is rotated, the diameter of the cylinder is 6cm, and the height is 4cm
Volume = bottom area * height = 3.14 * 3 ^ 2 * 4 = 113.04cm ^ 2
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