Multiple choice

A young man climbs a hill with a speed of 3 kilometers per hour and immediately returns from the top to the original place with a speed of 6 kilometers per hour. What is his average speed for the round trip?

  1. 3.75 Km/hr

  2. 4 Km/hr

  3. 4.5 Km/hr

  4. 4.75 Km/hr
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Average speed for a round trip with speeds v1 and v2 is 2 * v1 * v2 / (v1 + v2). Here v1 = 3 and v2 = 6. Average speed = 2 * 3 * 6 / (3 + 6) = 36 / 9 = 4 km/hr.

AI explanation

Using the harmonic mean formula for equal distances, the average speed equals twice the product of the two speeds divided by their sum. Substituting the given speeds gives 2 times 3 times 6 divided by the sum of 3 and 6. This calculates to 36 divided by 9, resulting in an average speed of 4 Km/hr.

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