The two cars leave each other from a and B cities 480 kilometers apart. They meet in four hours. The bus travels 58.5 kilometers per hour, and the truck travels how many kilometers per hour

The two cars leave each other from a and B cities 480 kilometers apart. They meet in four hours. The bus travels 58.5 kilometers per hour, and the truck travels how many kilometers per hour

Set up freight cars to travel x kilometers per hour
58.5+x=480÷4
58.5+x=120
x=61.5
A: trucks travel 61.5 kilometers per hour

The two cars run from a and B at the same time. Car a runs 52 kilometers per hour, while car B runs 56 kilometers per hour. The two cars meet 18 kilometers away from the midpoint

B is 4 kilometers per hour, and 18 kilometers away from the middle. Meeting means B has walked 36 kilometers more than a, 36 / 4 = 9 hours
So the distance is 9 x (52 + 56) = 972 km

It is known that the velocity of influenza bacteria moving in the windless air is 20 m / min, and the wind speed is 4 m / min. if influenza bacteria propagate from place a to place B downwind, and then return to place a, it will take five minutes (assuming that influenza bacteria do not stay) to calculate the distance between two places. Suppose the distance between two places is XM, then the correct equation is ()
A.(20+4)x+(20-4)x=5
B.20x+4x=5
C.x/(20+4)+x/4=5
D.x/(20+4)+x/(20-4)=5

D
X / (20 + 4) denotes the time required for downwind propagation from place a to place B
X / (20-4) is the time required to travel from land B to land a

Xiaohui measures the length of a wooden stick, and the approximate number obtained by rounding is 2.8 meters. Then the actual length range of this wooden stick is ()
A. Greater than 2m, less than 3m B. greater than 2.7m, less than 2.9m C. greater than 2.75m, less than 2.84m D. greater than or equal to 2.75m, less than 2.85m

When the decile of the original number is 7, the number on the percentile must be greater than or equal to 5; when the decile of the original number is 8, the number on the percentile must be less than 5. Therefore, the actual length range of the stick is greater than or equal to 2.75 meters and less than 2.85 meters