Question

On a 120km track, a train travels the first 30 km at a uniform speed of 30 km/hr. How fast

must the train travel the next 90 km so as to average 60 km/hr for the entire trip?

Answer 1

Hello freind !!

Let  total distance ( s) = 120 km ,initial distance ( s1) = 30km  , speed (v1) = 30km/h

Therefore time taken for first 30km = t1 = s1/v1 =30km/(30km/h)

t1= 1h

Average speed = 60km/h ,total distance travelled =  120 km

Total time taken(t) = 120 km /(60km/h )

  Hence, total time (t) = 2h

Remaining distance =s2 =120-30 = 90km

So,time taken for the remaining 90km (t2) = t -t1   

Therefore, t2 = 2h-1h  =1h

Speed (v2)  for the remining 90km = 90km/1h

Hence speed for the next 90km should be 90km/h

Please mark it as brainliest

Answer 2

Answer:

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