A man has to cover a distance of 1 km. He covers the first 200 km walking at a rate of 40 m/min. How fast should he run to cover the remaining distance, such that his average speed for the entire trip is 60 km/h.
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hello friend !
error in question: he have covered 200 m at first not 200km
now
we have
total distance / total time =60
total distance = 1km
total time = x + y
x is the time for first 200 m
at 40 m /min
y is remaining time
time = d/speed
x = 200/40 = 5min = 1/12 hours
now average speed =1km/ (1/12 +y) =60 (as given)
1000/60 = 1/12 +y
y = 1/60-1/12
y=-1/15
remaining distance = 800m
speed 800/-1/15
=-1200km/hr
it something impractical but it is the answer of the question or there is some other misprint in question
error in question: he have covered 200 m at first not 200km
now
we have
total distance / total time =60
total distance = 1km
total time = x + y
x is the time for first 200 m
at 40 m /min
y is remaining time
time = d/speed
x = 200/40 = 5min = 1/12 hours
now average speed =1km/ (1/12 +y) =60 (as given)
1000/60 = 1/12 +y
y = 1/60-1/12
y=-1/15
remaining distance = 800m
speed 800/-1/15
=-1200km/hr
it something impractical but it is the answer of the question or there is some other misprint in question
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