Radius: 4/2=2
2 * 2 * 3.14 * (13-9) = 50.24 cubic centimeters.
2. Xiao Qiang used the following methods to measure the volume of eggs. It is known that the inner diameter of glass on the ground is 8 cm. Do you know how big this egg is?
Didn't say anything?
3. A sports ground has 8 runways. In the figure, the width of each runway is 0. 122 cm, the diameter of circular runway at the entrance side plate is 3.6 cm, and the length of straight runway is 9.6 cm. How many cubic meters of sand do you need if you want to lay sand with a thickness of 15 cm in the innermost runway of this sports ground? (The ratio is 1: 1000)
Actual diameter length: 3.6 ÷11000 = 3600 cm = 36m radius: 36/2= 18m.
Actual straight runway length: 9.6 ÷11000 = 9600 cm = 96m.
Area:18 *18 * 3.14+36 * 96 = 4473.36 square meters.
Volume: 4473.36*0. 15≈67 1 m3
4. Now there is a weight whose mass is 1g, 2g, 3g, 4g and 8g respectively. How many different masses can be weighed with these weights on the balance?
5+10+10+5+1= 31species.
5. The height of the cylinder is 40cm, and the bottom area is 31.4cm2. Make it into a cone with a radius of 10 cm. What is the height of the cone?
40 * 3 1.4 * 3÷( 10 * 10 * 3. 14)= 12cm。
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