Answer:
53 1/3 km/h
Step-by-step explanation:
average speed = (total distance)/(total time)
average speed = distance/time
time * average speed = distance
time = distance/(average speed)
250 km at 75 km/h
distance = 250 km
time = (250 km)/(75 km/h) = 3.33333... hours
350 km at 70 km/h
distance = 350 km
time = (350 km)/(70 km/h) = 5 hours
200 km at 30 km/h
distance = 200 km
time = (200 km)/(30 km/h) = 6.6666... hour
total distance = 250 km + 350 km + 200 km = 800 km
total time = 3.33333... hours + 5 hours + 6.66666... hours = 15 hours
average speed = (total distance)/(total time)
average speed = (800 km)/(15 hours)
average speed = 53 1/3 km/h
The average speed of whole journey of the train is 45 km/hr
Average speed is the ratio of total distance travelled to total time taken. It is given by:
Average speed = total distance / total time
Given that a train travels 250 km with a average speed of 75 km/hr, hence:
75 = 250/time
time = 3.33 hours
It the travel 200 km with average speed of 30km/hr, hence:
30 = 200/time
time = 6.67 hours
The total distance = 200 km + 250 km = 450 km
The total time = 3.33 hr + 6.67 hr = 10 hours
Average speed = total distance/total time = 450 km/10 hours = 45 km/hr
The average speed of whole journey of the train is 45 km/hr
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