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The mass ratio of coal in pile a, pile B and pile C is 2:3:5. The average weight of these three piles of coal is 15 tons. How many tons is pile a less than pile B?
Four point five
The distance between the two cities is 540 km. The two trains drive from the two cities at the same time. Car a travels 60 km in 0.8 hours, 15 km faster than car B. how long does it take
Don't use equations
V a = 60 / 0.8 = 75 km / h, v b = 75-15 = 60, t = 540 / (75 + 60) = 4 hours
The weight ratio of the original cement of the two construction teams is 5:3. When the construction team a delivers 36 tons of cement to the construction team B, the weight ratio of the two construction teams is 4:6. How many tons of the original cement of the construction team a?
Total cement: 36 ÷ (5 / 8-4 / 10) = 160 (tons)
Original cement of team a: 160 ÷ (5 + 3) × 5 = 100 (tons)
A: 100 tons of original cement
The mass ratio of pile a and pile B is 3:5, the mass of pile B is 200 tons, and the mass of pile a is 100 tons___ Tons
200 △ 5 × 3 = 40 × 3 = 120 tons; a: the mass of coal in pile a is 120 tons, so the answer is: 120
Both cars are moving in a straight line at a constant speed. Car a is 20 meters in front of car B and moves 2 seconds earlier than car B. the speed of car a is 2 meters per second and that of car B is 10.8 kilometers per hour
1. How long does it take car B to catch up with car a?
2. When car B overtakes car a, how far is car a from the starting point?
Set T seconds for B to catch up with a
First, unify the speed of unit B: 10.8km/h = 10.8 / 3.6m/s = 3m / s
A is 20 meters ahead of B and two seconds ahead of B = > 20 + 2 * 2 + 2T = 3T
The solution is t = 24s
A: after 24 seconds, B overtakes a
This can be done with relative velocity: the relative velocity of a and B is: 10.8-2 = 8.8m/s, the distance S = 20m, so the time t = 20m / 8.8m/s = 2.3S (accurate to a significant number)
S can be made by a or B, s = 20 + 2 * 2.3 = 10.8 * 2.3 = 24.6m
Party A and Party B transport a batch of cement together. At the end of the transport, Party A transported 715 tons of cement. The ratio of the tons transported by Party B to Party A is 1:2. How many tons of cement are there in total?
1 + 2 = 318 ^ (23-715) = 18 ^ 315 = 90 (tons) a: there are 90 tons of this batch of cement
The total weight of coal in the third pile of a, B and C is 15 tons, and the mass ratio is 2:3:5
Then the weight of coal (a, B and C) is () and ()
、（）
2X+3X+5X=15
X=1.5
A = 2x = 3 tons
B = 3x = 4.5 tons
C = 5.5t
3：4。 5：7。 Five
15/(2+3+5)=1.5
2 * 1.5 = 3 tons
3 * 1.5 = 4.5 tons
5 * 1.5 = 7.5 tons
3 tons
4.5 tons
7.5 tons
Car a and car B leave from both places at the same time. They meet 8 hours later. Car a travels 80 kilometers per hour. Car B's speed is 1.02 times that of car A. how many kilometers are there between the two places?
80 × 8 + (80 × 1.02) × 8 = 80 × 8 + 81.6 × 8, = (80 + 81.6) × 8, = 161.6 × 8, = 1292.8 (km), a: the distance between the two places is 1292.8 km
Party A and Party B transport a batch of cement together. At the end of the transport, Party A transported 715 tons of cement. The ratio of the tons transported by Party B to Party A is 1:2. How many tons of cement are there in total?
1 + 2 = 318 ^ (23-715) = 18 ^ 315 = 90 (tons) a: there are 90 tons of this batch of cement
The total weight of coal in pile a, B and C is 15 tons, and the mass ratio is 2:3:5, then the weight of coal in pile a, B and C is (), (), ()
If the mass ratio of coal in pile a, B and C is 2:3:5, the weight of coal in pile a, B and C is (15 * 2 / (2 + 3 + 5) = 3), (15 * 3 / 10 = 4.5) and (15 * 5 / 10 = 7.5)
Three
Four point five
Seven point five
15 divided by (2 + 3 + 5)
=15 divided by 10
=1.5 one copy
1.5 times 2 = 10 A
1.5 times 3 = 15B
1.5 times 5 = 25 C
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