Answers

2015-01-19T12:59:22+05:30
Let the distance be  d KM

so when speed is 4 KM/hr    Time  T1= d/4 hr  (10 min earler than schd time)
when speed is 3 KM/hr         Time  T2=d/3 hr    (10 min late than schd time)
difference  between T1 and T2 is 20 min = 20/60 hr
                                                            = 1/3 hr
T2-T1=1/3
d/3-d/4= 1/3
(4d-3d)/12= 1/3
d=12/3
d= 4 KM
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