(1) cylindrical oil drum, measured from the inside, with a bottom diameter of 40cm and a height of 50cm.
If 1 cubic decimeter can hold 0.85 kilograms of oil, how many kilograms can this oil drum hold?
Bottom radius: 40 ÷ 2 = 20 (cm)
Oil drum volume: 3. 14× 20× 20× 50 = 62800 (cubic centimeter) = 62.8 (liter)
Loadable diesel oil: 62.8× 0.85 = 53.38kg.
The seventh question-
The original volume of toothpaste used by each person every day is 3.14x (0.4/2) (0.4/2) x2 = 0.255438+02.
The original volume of toothpaste used in one year is 0.2512x365 = 91.688 cubic centimeter.
The volume of toothpaste used per person per day is 3.14x (0.5/2) (0.5/2) x2 = 0.3925.
At present, the volume of toothpaste used in one year is 0.3925x365 = 143.2625 cubic centimeters.
Everyone uses143.2625-91.688 = 51.5745 cubic centimeters more than before.
The reserved integer is about 52 cubic centimeters.