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Impossible Math Problem

Impossible Math Problem - 4 November

Suppose you drive to a picnic spot at 20 mph, then how fast you must go while returning back home on the same route such that your average speed becomes 40 mph ?

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  1. According to the formula Average speed =(Total Distance travel/Total time taken)
    if A is the distance-then total distance travel in to and fro is 2A
    Time taken while going is A/20
    Time taken while cmg is A/X ( X is the speed )
    Average speed = 2A/((A/20)+(A/X)) =40
    Solving this , we get AX= AX+20
    Conclusion: It is quite impossible to get average speed of 40MPH in this case

  2. Not possible as in the onward journey you consume the total time required to make the average as 40 kmph