A car travels 20 miles at 30 mph, then 10 miles at 60 mph. What is the mean speed for the whole journey of 30 miles
A: 36
B: 40
C: 42
D: 45
A: 36
B: 40
C: 42
D: 45
举一反三
- The time it took car P to travel 600 miles was 2 hours less than the time it took car R to travel the same distance. If car P’s average speed was 10 miles per hour greater than that of car R, what was car R’s average speed, in miles per hour ？（） A: 40 B: 50 C: 60 D: 70 E: 80
- 11. The speed of this car was 160 miles ____ hour.
- A car travels at a rate of 50 miles per hour.How long will it take to travel 300 miles（） A: 250hours B: 6hours C: 1/6hours D: 15000hours
- A．At least 14 miles an hour.B．At least 40 miles an hour.C．At most 40 miles an hour.D．A A: At least 14 miles an hour. B: At least 40 miles an hour. C: At most 40 miles an hour. D: At most 14 miles an hour.
- Two cars left the same town traveling in the same direction. Car A traveled 40 miles per hour and left at 3:20. Car B traveled 50 miles per hour and left at 4:40. At what time will car B catch up with car A A: 10:00 B: 9:00 C: 8:40 D: 7:20 E: (E) 6:10