5. Class 1 took a car for a spring outing. The car drove at a speed of 40 km / h for 30 minutes, then drove into the expressway and drove for 45 minutes at a speed of 80 km / h Find the average speed of a car

5. Class 1 took a car for a spring outing. The car drove at a speed of 40 km / h for 30 minutes, then drove into the expressway and drove for 45 minutes at a speed of 80 km / h Find the average speed of a car

The average speed of a car is equal to the total journey divided by the total time: (40 *. 5 + 80 * 0.75) / (. 5 +. 75) = 80 / 1.25 = 64km / h

A car goes from place a to place B. If 80 kilometers per hour, it will arrive at place B at the scheduled time,
Just three hours late. How many hours does it take for this bus to go from place a to place B

If the original time is x hours, then
80x=60(x+3)
80x=60x+180
20x=180
x=9
It was originally scheduled for nine hours

At the same time, the two vehicles depart from a and B. car a travels 60km per hour, car B travels 50km per hour, passing through 4 hours, with a total of 80%?

(60+50)*4/80%
=110*4/80%
=440/80%
=550 km