Multiple choice

A vehicle travels half or the total distance with speed $36 km/h$ and next half with $54 km/h$. The average speed is

  1. $12ms^{-1}$
  2. $12.5ms^{-1}$
  3. $43.2km/h$
  4. $7.5ms^{-1}$
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C Correct answer
AI explanation

When a vehicle travels equal distances at two different speeds, the average speed is found using the harmonic mean formula: 2uv divided by (u + v). Substituting the given speeds of 36 km/h and 54 km/h gives 2 times 36 times 54 divided by 90, which equals 3888 divided by 90 or 43.2 km/h. This matches the required result perfectly.

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