Multiple choice

A car covers a distance of 48 km at a speed of 40 km/h and another 52 km with a speed of 65 km/h. What is the average speed of the car (in km/h) for the total distance covered?

  1. $52$
  2. $50$
  3. $52.5$
  4. $54$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed is total distance divided by total time. Total distance = 48 + 52 = 100 km. Time for first part = 48/40 = 1.2 hours. Time for second part = 52/65 = 0.8 hours. Total time = 1.2 + 0.8 = 2 hours. Average speed = 100/2 = 50 km/h. The harmonic mean of speeds weighted by distance gives the correct result.

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