Multiple choice

Naresh Kumar drives his car to his office with the speed of $40$ km per hour and returns along the same route with the speed of $60$ km per hour. Find his average speed for the entire round trip.

  1. $50km/h$
  2. $54km/h$
  3. $48km/h$
  4. $44km/h$
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C Correct answer
Explanation

Average speed for a round trip with speeds v1 and v2 is (2 * v1 * v2) / (v1 + v2). (2 * 40 * 60) / (40 + 60) = 4800 / 100 = 48 km/h.

AI explanation

When equal distances are traveled at two different speeds, the average speed is calculated using the harmonic mean formula 2xy divided by (x plus y). Substituting the speeds 40 and 60 gives 2 times 40 times 60 divided by 100, which simplifies to 4800 divided by 100. The average speed for the entire round trip is 48 km/h.

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