Multiple choice

A boy goes to market from his home with speed of 40 km/h and returns back from market to his home along the same path with speed of 10 km/h. The average speed of the boy for the entire journey is

  1. 32 km/h

  2. 16 km/h

  3. 40 km/h

  4. Zero
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Since the distance to the market and back is the same, the average speed is the harmonic mean of the two speeds. This is calculated as 2 * 40 * 10 / (40 + 10) = 16 km/h.

AI explanation

Because the boy travels equal distances at two different speeds, we use the average speed formula for equal distances: 2xy / (x + y). Substituting the speeds of 40 km/h and 10 km/h gives (2 * 40 * 10) / (40 + 10). This simplifies to 800 / 50, resulting in an average speed of 16 km/h.

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