Question 78

A Person travel Equilateral triangular area with the speed of 24kmph, 36kmph, and 72kmph along the planes of the triangular field. Find the average speed of the journey.

Solution

Since, the distance travelled is equal on the three sides, hence average speed will be the harmonic mean of the speeds.

= $$\frac{3}{\frac{1}{24}+\frac{1}{36}+\frac{1}{72}}$$

= $$\frac{3}{\frac{3+2+1}{72}}$$

= $$\frac{3}{6}\times72=36$$ km/hr

=> Ans - (D)

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