19×12×1/3 = 76 cubic centimeters.
2. A pile of coal is conical. The bottom radius is 1.5m and the height is1.1m. What is the volume of this pile of coal?
1.5×1.5× 3.14×1.1.3 = 2.5905 cubic meters.
If each cubic meter of coal weighs about 1.4 tons, how many tons is this pile of coal? (Keep the whole ton. )
1.4×2.5905≈4 tons
3、
(1) Find the surface area and volume of a cylinder with a diameter of 6 cm and a height of 12 cm.
superficial area
6× 3.14×12+(6 ÷ 2 )× (6 ÷ 2 )× 3.14× 2 = 282.6 square centimeters.
roll
(6 ÷ 2) × (6 ÷ 2 )× 3.14×12 = 339.12 cubic centimeter.
(2) Find the surface area and volume of a cuboid with a length of 15cm, a width of 10cm and a height of 20cm.
superficial area
( 15× 10+ 15×20+ 10×20)×2 = 1300 cm2。
roll
15× 10× 20 = 3000 cubic centimeters.
(3) Find the surface area and volume of a cylinder with a diameter of 14cm and a height of 5cm.
superficial area
14× 3.14× 5+(14÷ 2 )× (14÷ 2 )× 3.14× 2 = 527.52 square centimeters.
roll
(14 ÷ 2) × (14 ÷ 2 )× 3.14× 5 = 769.3 cubic centimeters.
4. A cylindrical grain depot, measured from the inside, with a radius of 1.5m and a height of 2m. If each cubic meter of corn weighs about 750 kilograms, how many tons of corn can this grain depot hold?
The volume is
1.5×1.5× 3.14× 2 =14.13 m3.
This grain depot can store corn.
14. 13×750 = 10597.5kg = 10.5975t。
The school should build a fence between the teaching area and the playground. The original plan was to use 35 cubic meters of earth and stone. Later, the door was opened for an extra month, which reduced the amount of earthwork. How many cubic meters of earth and stone are used now?
Incomplete data
6. Two cylinders with equal bottom areas, one with a height of 405 decimeters and a volume of 8 1 cubic decimeter. The other one is 3 meters high. What is its volume?
The bottom area is
81405 = 0.2 square decimeter
The volume of the other one is
0.2× 3 = 0.6 cubic decimeter