Question

a scientist travel at 36 km per hour for 5 hour and at 45 km per hour for 4 hour . find his average speed do whole journey.
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Answer 1

Answer:

40 kmph

Step-by-step explanation:

Average speed = total distance/ total time

Total time = 5 hours + 4 hours = 9 hours

Distance = speed * time

Distance in first five hours = 36*5

Distance in first five hours= 180 km

Distance in next four hours = 45*4

Distance in next four hours = 180 km

Total distance = 180+180

Total distance = 360 km

Average speed = 360/9

Average speed = 40 km/h