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If a person travel 39 km at a speed of 26 km/h, another 39 km at a speed of 39 km/h and 39 km again at a speed of 52 km/h . Then find the average speed of entire journey
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- 35 km/h
- 35 km/h
- 36 km/h
- 40 km/h
Correct Option: C
Average speed of entire journey
= (39 + 39 + 39)/(39/26 + 39/39 +39/52)
= 3/(1/26 + 1/39 +1/52)
= 3/[(6 + 4 + 3)/156]
= 3 x 156/13 = 36 km/h
