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Mathematical application problems (formula calculation) (1) One day, 8000 people visit an education website, 2 out of 25 students and 3 out of 40 teachers? (2) There is a round iron sheet with a radius of 20 cm. If 40% of this iron sheet is used, how many square centimeters are left? (3) If the ratio of 7:4 is used to raise carp and crucian carp, the number of fry of carp is 1200 more than that of crucian carp? (4) There are 45 kg apples in basket A. after 1 / 5 of basket a is used and 1 / 7 of basket B is used, the remaining two baskets of apples are the same. How many kg are the apples in basket B?
18000 * (2 / 25 + 3 / 40) = 1240 people,
2,20 * 20 * 3.14 * (1-0.4) = 753.6 cm2
3,1200/（7-4）=400
Carp fry: 400 * 7 = 2800
Crucian carp fry: 400 * 4 = 1600
4. After use, there is 45 * (1-1 / 5) = 36 kg
When one seventh of basket B is used, it has 36 kg: 36 / (1-1 / 7) = 42 kg
Mathematical application problem formulation and calculation
To build a highway, one fourth of the total length has been built, and the remaining one fifth has been built. At this time, there are still six kilometers from the midpoint. How many kilometers is the highway long?
Method 1 6 / [(1 / 2) - (1 / 4) - (1 / 5) * (1-1 / 4)] = 60 (km)
Method 2: the total length is x km
(1/4)*x+(1/5)*(1-1/4)*x+6=(1/2)*x
x=60
Practical problems of cylinder and cone in Grade 6
(1) A cylindrical part tube, 70cm in length, 20cm in outer diameter and 10cm in inner diameter, what is the volume of the part?
(2) A conical sand pile with a bottom radius of 3 meters and 7 meters can be used to pave a road with a thickness of 4 cm on a 15 meter wide road. How many meters can it pave?
(3) There is a pile of cone-shaped Triassic soil on the construction site. The perimeter of the bottom surface is 37.68m and the height is 5m. How many meters can the Triassic soil be paved on the 15.7m wide road with a thickness of 4cm?
(4) Cast a cylinder iron block with a bottom area of 6.28 square decimeters and a height of 9 decimeters into a cone with a bottom area of 12.56 square decimeters. What is the height of the cone?
（1）3.14×[（20/2）×（20/2）-（10/2）×（10/2）]×70
=3.14×[100-25]×70
=3.14×75×70
=16485 (CC)
(2) Sand pile volume: 3.14 × 3 × 3 × 2.7 × 1 / 3 = 25.434 M3
4cm = 0.04m
Capacity: 25.434 ÷ (15 × 0.04) = 42.39m
(3) Bottom radius: 37.68 △ 3.14 △ 2 = 6M
Volume of triad: 3.14 × 6 × 6 × 5 × 1 / 3 = 188.4 M3
4cm = 0.04m
Paveable: 188.4 ÷ (15.7 × 0.04) = 300m
(4) 6.28 × 9 / 3 / 12.56 = 13.5 decimeters
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