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The speed of a railway engine is 42 kmph when no compartment is attached, and the reduction in speed is directly proportional to the square root of the number of compartments attached. If the speed of the train carried by this engine is 24 kmph when 9 compartments are attached, the maximum number of compartments that can be carried by the engine is

  1. 49
  2. 48
  3. 46
  4. 47

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Answer A)49

With no compartment engine speed 42kmph

24 kmph speed when 9 compartment attached

reduction in speed is directly proportional to the square root of the number of compartments attached

So, when 9 compartment attached speed reduction 18kmph

18 ∞ √9

18=3k

or, k=6

So, for 42kmph

42=6√x [where x number of compartment]

or, x=49
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