2. Original surface area+increased surface area, and the increased surface area is the sum of all the side areas of six small holes (2×2×4×6=96 cm2), so its surface area is 6×6×6+96=3 12 cm2.
3, unified unit 0.8 meters =8 decimeters, 25 cm =2.5 decimeters.
The volume of a cubic water tank is 4 and the bottom area of a cubic water tank is 8×2.5.
= 64/20 = 3.2 decimeters
4. The volume is unchanged. Similar to the three questions, the unified unit is 2 cm =0.2 decimeter.
Product of volume, length and thickness of cubic billet
= 4×4×4(64×0.2)= 0.2 (decimeter)
5. The tonnage burned the next day is 18× two thirds = 12 tons, and the tonnage burned the next day is 18+ 12=30 tons.
According to the meaning of fractional division, the total tonnage is 30÷60%=50 (tons), and then what is burned is equal to the rest, that is, 50-30=20 (tons).
6. The number of girls has not changed, and the unit is "1". The score rate of 1 boys is 70% minus two thirds, so according to the meaning of fractional division, the number of girls is 1÷(70%-2/3)=30 (people), so the total number is 30.
Seven ... Meditation ...
What do you mean?
It took me 40 minutes.