A cylindrical tin oil barrel is filled with gasoline. Pour 2 / 3 of the gasoline in the barrel, and there are 36 liters left. It is known that the height of the oil barrel is 8 decimeters, and what is the bottom area of the oil barrel? To pave a piece of land, it's 2400 fast to use 3-decimeter-long square bricks, but how fast to use 2-decimeter-long square bricks instead

A cylindrical tin oil barrel is filled with gasoline. Pour 2 / 3 of the gasoline in the barrel, and there are 36 liters left. It is known that the height of the oil barrel is 8 decimeters, and what is the bottom area of the oil barrel? To pave a piece of land, it's 2400 fast to use 3-decimeter-long square bricks, but how fast to use 2-decimeter-long square bricks instead

[question 1]
The volume of oil is 36 (1-2 / 3) = 108 liters
The bottom area is 108 △ 8 = 13.5 square decimeters
[question 2]
The area of this land is 3 × 3 × 2400 = 21600 square decimeters
Later, the area of each brick was 2 × 2 = 4 square decimeters
So at least 21600 △ 4 = 5400 pieces are needed

A cylindrical pool with a bottom radius of 6 meters and a depth of 3.5 meters
1) What is the floor area of this pool
2) How many tons of water can this pool hold
3) Apply a layer of cement on the ground and around the pool. How many square meters is the area covered with cement?

1. Floor area = 6 * 6 * 3.14 = 113.04 square meters
2. Capacity = 113.04 * 3.5 * 1 = 395.64 tons
3. Area = 113.04 + 6 * 2 * 3.14 * 3.5 = 244.92m2

A piece of iron wire is 5 / 4 meters long. For the first time, it takes 1 / 4 of the total length. For the second time, it takes 5 / 8 of the total length. How many meters are used each time? How many parts of the total length are shared? How many meters are left?

For the first time, (4 / 5) × (1 / 4) = 1 / 5m
(4 / 5) × (5 / 8) = 1 / 2m for the second time
Share 1 / 4 + 5 / 8 of the total length = 7 / 8
4 / 5-1 / 5-1 / 2 = 1 / 10m left