Multiple choice

A car travels half the distance with constant speed of 40 kmph and the remaining half with a constant speed of 60 kmph. The average speed of the car in kmph is

  1. 40

  2. 45

  3. 48

  4. 50
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C Correct answer
Explanation

Average speed = (2 * v1 * v2) / (v1 + v2) = (2 * 40 * 60) / (40 + 60) = 4800 / 100 = 48.

AI explanation

Because equal distances are traveled at two different speeds, use the harmonic mean formula for average speed: 2xy / (x + y). Plug in the speeds 40 kmph and 60 kmph to get (2 * 40 * 60) / (40 + 60), which simplifies to 4800 / 100. The average speed of the car is 48 kmph.

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