A man completes half of a trip at 30 miles per hour and the other half at 60…
2022
A man completes half of a trip at 30 miles per hour and the other half at 60 miles per hour. If the whole trip is 20 miles, how much time will he take to complete the trip?
Answer: A. 30 minutes — Total distance = 20 miles. Half distance = 10 miles each. Time for first 10 miles at 30 mph = 10/30 = 1/3 hour (20 minutes) Time for second 10 miles at 60 mph…
- A.
30 minutes
- B.
45 minutes
- C.
60 minutes
- D.
75 minutes
Attempted by 171 students.
Show answer & explanation
Correct answer: A
Total distance = 20 miles. Half distance = 10 miles each. Time for first 10 miles at 30 mph = 10/30 = 1/3 hour (20 minutes)
Time for second 10 miles at 60 mph = 10/60 = 1/6 hour (10 minutes)
Total time = 1/3 + 1/6 = 1/2 hour = 30 minutes Check using average speed for equal distances (harmonic mean): Average speed = 2 * 30 * 60
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