1. The students made 20 cylindrical lampshades with colored paper, each with a height of 35cm and a circumference of 47. 1cm. How much colored paper do you need at least?

47. 1×35×20=32970cm？

47. 1÷3. 14÷2=7.5

3. 14×7.5? = 176.625cm？

32970

176.625=33 147cm？

2. A conical sand pile with a bottom area of 28.26m? The height is 2.5m How many meters can you use this pile of sand to pave a pavement with a thickness of 2cm on a pavement with a width of 10m?

28.26×2.5=70.65

70.65 ÷10 ÷ 0.02 = 353.25m.

There is a square piece of wood with a side length of 4dm. Make this piece of wood into the largest cylinder. What is the volume of this cylinder?

3. 14×2? ×4=50.24dm？