The maximum carrying capacity of a car with a roof is 10t, and its volume is 12m ^ 3. Now it needs to transport two kinds of goods, steel and wood Now we need to transport two kinds of goods, steel and wood. The calculation shows: how should these two kinds of goods be matched to make full use of the car's compartment? (the density of steel is 7.9 × 10 ^ 3kg / m ^ 3, the density of wood is 0.5 × 10 ^ 3kg / m ^ 3)

The maximum carrying capacity of a car with a roof is 10t, and its volume is 12m ^ 3. Now it needs to transport two kinds of goods, steel and wood Now we need to transport two kinds of goods, steel and wood. The calculation shows: how should these two kinds of goods be matched to make full use of the car's compartment? (the density of steel is 7.9 × 10 ^ 3kg / m ^ 3, the density of wood is 0.5 × 10 ^ 3kg / m ^ 3)

Let the mass of steel be m and the mass of wood be m
Then M + M = 10000
M/(7.9×10^3)+m/(0.5×10^3)=12
Solution
M=4.27t m=5.73t
Therefore, 4.27t steel and 5.73t wood can be transported to make full use of the car compartment

1. Transport a batch of goods by a train with the same carrying capacity. If each train is loaded with 5 tons, it can fill 12 cars. If each train is loaded with 4 tons, how many cars can be filled
2. There were 45 students in class 6 (1). In the new semester, there are two boys and one girl. This is the number of girls, which is seven ninth of the number of boys. How many boys and girls are there in this class?
3. Xiao Ming goes to school by bike. If he walks 100 meters per minute, he can get to school in 45 minutes. One day, five minutes after Xiao Ming left, his father found that Xiao Ming's math book was left at home, so he chased him at the speed of 150 meters per minute. He asked: can my father catch up with Xiao Ming before he arrives at school? If you can, how many meters away from the school?

1
It can hold x cars
5：4=x:12
x=5x12÷4
x=15
two
Boys are now (45 + 2 + 1) / (1 + 7 / 9) = 48 / 16 / 9 = 27
Boys: 27-2 = 25
Female 45-25 = 20
three
Xiaoming walks 5x100 = 500m
Catch up time 500 (150-100) = 10 minutes
We can catch up
100x (45-10-5) = 3000m from school
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