A boat covers a distance of 30 km downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in km/hr ?



A boat covers a distance of 30 km downstream in 2 hours while it takes 6 hours to cover the same distance upstream. What is the speed of the boat in km/hr ?

A. 5

B. 7.5

C. 10

D. 12

Answer : C. 10


Explanation :

  • Speed of boat downstream
    = Distance covered / Time taken
    = 30/2
    = 15 km/h
  • Now, speed of boat upstream
    = Distance covered / Time taken
    = 30/6
    = 5 km/h
  • Now, speed of boat = (Speed downstream + Speed upstream)/2
    = (15 + 5)/2
    = 20/2
    = 10 km/h.

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