The average speed of the complete round trip is 61.12 km / h.
We need to know about the average speed to solve this problem. The average speed can be determined as the total distance divided by the total time. It can be written as
v = d / t
where v is average speed, d is distance and t is time.
From the question above, we know that
d1 = 290 km
v1 = 91 km/h
t lunch = 1 hour
d2 = 290 km
v2 = 54 km/h
Find the time during the outgoing
v1 = d1 / t1
t1 = d1 / v1
t1 = 290 / 93
t1 = 3.12 hours
Find the return time
v2 = d2 / t2
t2 = d2 / v2
t2 = 290 / 54
t2 = 5.37 hours
Hence, the total time
t = t1 + t2 + t lunch
t = 3.12 + 5.37 + 1
t = 9.49 hours
Find the average speed
v = d / t
v = (290 + 290) / 9.49
v = 61.12 km / h
For more on average speed at: https://brainly.com/question/24739297
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