Question

8).
A train travels in a straight line at a constant speed 60 km/hr for a distance of 120km. The train then takes a stoppage of the and finally travels another distance of 240km
in the same direction at a constant speed of 80 km/hr to reach its destination. What is the average speed of train during the whole journey
50 km/hr
60 km/hr
70 km/hr
72 km/hr​

Answer 1

Answer:

Average speed = 72 km / hr

Explanation :

speed 1 = 60 km/hr

distance 1 = 120 km

speed 2 = 80 km/hr

distance 2 = 240 km

speed 1 = distance 1 / time 1

60 = 120 / t1

60 × t1 = 120

t1 = 120 / 60

t1 = 2 hr

time 1 = 2hr

speed 2 = distance 2 / time 2

80 = 240 / t2

t2 = 240 / 80

t2 = 3 hr

time 2 = 3 hr

Average speed = total distance covered / total time taken

Avg. speed = distance 1 + distance 2 / time 1 + time 2

Avg. speed = 120 + 240 / 2 + 3

Avg. speed = 360 / 5

Average speed = 72 km / hr