A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.

–1 vote

A man complete a journey in 10 hours. He travels first half of the journey at the rate of 21 km/hr and second half at the rate of 24 km/hr. Find the total journey in km.

+3 votes

Best answer

Let's total time=t=10 hrs= 600 min............(i)

total distance travelled=x

half distance=d1=d2=x/2........................................(ii)

Speed=s1=21 km/hr= 0.35 km/min..............................(iii)

s2= 24 km/hr= 0.4 km/min.................................(iv)

t=d/s=[(d1/s1)]+[(d2/s2)]

600 = [( x/2) / 0.35] + [( x/2) / 0.4]

600 = x/2* [ 2.857 + 2.5 ]

x = 600*2 / 5.357

x = 224 km

...

as speed is given 21 and 24 in 1 hr

then min distance it will cover in 10hr will be 210 km

and max 240 km . How it will be 1600 km??