B It takes 6+2 = 8 days.
2/3/( 1/6+ 1/8)
= 16/7 days
2. Immerse a cylindrical iron block with a radius of 2 cm into a water tank with a length of 3 1.4 cm and a width of 10 cm, and the water level will rise by 1 cm. Find the height of this cylindrical block.
3 1.4* 10* 1/(2*2*3. 14)
=3 14/ 12.56
= 25 cm
The number of female workers in the factory is 80% of that of male workers. Because of the need of work, 30 female workers were mobilized. At this time, the number of female workers is more than that of male workers 10%. How many people are there in this factory?
There are x male workers.
80%*x+30=x+x* 10%
x= 100
A piece of land is 420 hectares, and a tractor plowed three-sevenths of this land in three days. According to this calculation, how many days will it take to plow this land? (solved by proportional method)
420/(420*3/7 / 3)-3
=420/60-3
= 4 days
5. A cylinder with a height of 5 decimeters is cut into equal parts along the bottom diameter; After two parts, the surface area increased by 60 square decimeters. What is the volume of this cylinder?
60/2/5 = 6 decimeters
3. 14*(6/2)(6/2)*5
= 14 1.3 cubic decimeter
6. Distance from Wuxi to Luoshe 15km. Xiaoming rode from Luoshe to Wuxi for a while, walking at half the speed of cycling. If it takes half an hour to ride a bike and 2.5 hours to walk, what is the riding speed?
Suppose the riding speed is x km/h.
0.5x+2.5x/2= 15
x=
7. There is a batch of goods in the warehouse. It takes four times to use the cart and six times to use the car. If a small cart can hold 2 tons at a time, how many tons can a big cart hold at a time?
6*2/4=3 tons
8. For a plot of land, it takes 15 hours for tractor A to plow alone, and 10 hours for tractor B to plow alone. Two tractors plowed for 2 hours at the same time, and the rest was plowed by tractor A. How many hours does it take to plow?
[ 1-( 1/ 15+ 1/ 10)*2]/ 1/ 15
= 10 hour
Two. Fill in the blanks:
1. Forge a cylinder with a bottom radius of 2 cm and a length of 30 cm into a cube with a volume of (376.8 cubic centimeters).
2. For a project, it takes 65,438+00 days for Party A to complete it alone and 65,438+05 days for Party B to complete it alone, so the cooperation between Party A and Party B takes (6) days.
3. The sum of the same scores of three molecules is 1.05, and the ratio of the three denominators is 4: 2: 1. These three scores are (5/3, 5/6, 5/ 12).
4. The remainder of a number divided by 2.3.4 is 1.2.3, so the minimum number of this number is (1 1).
The denominator of a simple fraction is multiplied by one third, and the numerator is divided by one half to get 7, so this number is (7/6).
6. The number greater than three-thirds is (16/2 1).
7. The area of a rectangle is equal to 625. If it is replaced by a square with the same area, the side length of the square is (25).