Multiple choice

We drive a distance of $1 km$ at $16 km/h$. Then we drive an additional distance of $1 km$ at $32 km/h$. What is our average speed?

  1. $21.3 km/h$
  2. $22 km/h$
  3. $23 km/h$
  4. $24 km/h$
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A Correct answer
Explanation

Average speed = Total distance / Total time. Total distance = 1 + 1 = 2 km. Time 1 = 1/16 hours. Time 2 = 1/32 hours. Total time = 1/16 + 1/32 = 3/32 hours. Average speed = 2 / (3/32) = 64 / 3 = 21.33 km/h.

AI explanation

Because the distances are the same, the average speed is calculated using the harmonic mean formula: twice the product of the speeds divided by their sum. The calculation is twice 16 multiplied by 32, divided by the sum of 16 and 32. This results in 1024 divided by 48, which equals 21.3 km/h.

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