Question

The distance between Delhi and Agra is 200 km. A train travels the first 100 km at a speed of 50 km/h. How fast must the train travel the next 100 km, so as to average 70 km/h for the whole journey?​

Answer 1

Answer:

116.67 km/h

Explanation:

Average speed = total distance ÷ total time

70 = 200 ÷ total time

total time = 200÷70 = 20/7

Time in first half will be 2 hours since the train will take 2 hours to travel 100km at a rate of 50km/h.

speed = distance ÷ time

speed = 100 ÷ (20/7 - 2)

speed = 100 ÷ 6/7

speed = 700 ÷ 6 = 116.67