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A rail engine is moving at a uniform speed of 30 km per hour towards a place "X". When the engine

is still 20 km away from "X", an insect starts at "X" and shuttles between "X" and engine at a uniform

speed of 42 km per hour. The total distance travelled by the insect, by the time engine

reaches "X" is ?

Here in this case the rail engine is moving at an uniform speed of 30 km/hr towards a place X .

While the engine is 20 Km from X then an insect starts moving at X .

So the taken by the engine to reach the X = t = 20 /30 = 0.6666 hr

So the Distance travelled by the insect with an average sped of 42 km /hr in that time is ,

S

_{insect}= 42 x 0.6666 = 28 km .

Regards

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