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Question 4 the Day - Speed, Time and Distance
December 16, 2003
Steve traveled the first 2 hours of his journey at 40 mph and the remaining 3 hours of his journey at 80 mph. What is his average speed for the entire journey?
| (A) | 60 mph |
| (B) | 56.67 mph |
| (C) | 53.33 mph |
| (D) | 64 mph |
| (E) | 66.67 mph |
Correct Answer Choice (D)
Solution:
Average speed of travel = 
Total distance traveled by Steve = Distance covered in the first 2 hours + distance covered in the next 3 hours.
Distance covered in the first 2 hours = speed * time = 40 * 2 = 80 miles
Distance covered in the next 3 hours = speed * time = 80 * 3 = 240 miles
Therefore, total distance covered = 80 + 240 = 320 miles
Total time taken = 2 + 3 = 5 hours.
Hence, average speed =  = 64 miles per hour.
Note: If Steve had traveled equal amount of time in each of the two speeds, then his average speed will be the arithmetic mean (or simple average) of the two speeds.
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