Two cities P and Q are 360 km apart. A car goes from P to Q at a speed of 40…
2020
Two cities P and Q are 360 km apart. A car goes from P to Q at a speed of 40 km per hour and returns to P at a speed of 50 km per hour. What is the average speed of the car?
Answer: A. 44.44 km per hour — Average speed is total distance divided by total time, not the arithmetic mean of the two speeds. The car travels 360 km from P to Q and 360 km from Q to P,…
- A.
44.44 km per hour
- B.
48 km per hour
- C.
50 km per hour
- D.
55 km per hour
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Correct answer: A
Average speed is total distance divided by total time, not the arithmetic mean of the two speeds. The car travels 360 km from P to Q and 360 km from Q to P, so total distance = 720 km. Time from P to Q = 360/40 = 9 hours. Time from Q to P = 360/50 = 7.2 hours. Total time = 16.2 hours. Average speed = 720/16.2 = 44.44 km per hour. Therefore, the correct answer is 44.44 km per hour.