Multiple choice

Ritu travels from home to college at 30 kmph. On reaching the college gate, she realizes that it was a Sunday and hence immediately returns home by the same route at 50 kmph. Find her average speed for the entire journey.

  1. 36 kmph

  2. 37.5 kmph

  3. 40 kmph

  4. 48 kmph
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, 2 * 30 * 50 / (30 + 50) = 3000 / 80 = 37.5 kmph.

AI explanation

Since the distances traveled in both directions are equal, we apply the harmonic mean formula for average speed, which is 2xy/(x+y). Substituting the forward speed of 30 kmph and return speed of 50 kmph gives an average speed of (2*30*50)/(30+50). Calculating this yields 3000/80, resulting in an average speed of 37.5 kmph.

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