SOLUTION: A man jogged 3.5 km/h in 20 min. He then walked the remainder of the 5.5 km at an average speed of 5 km/h. Given that he did not stop to rest during the entire distance of 5.5 km,

Question 1020035: A man jogged 3.5 km/h in 20 min. He then walked the remainder of the 5.5 km at an average speed of 5 km/h. Given that he did not stop to rest during the entire distance of 5.5 km, calculate his average speed in km/h for the Whole journey.
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
A man jogged 3.5 km/h in 20 min.
He then walked the remainder of the 5.5 km at an average speed of 5 km/h.
Given that he did not stop to rest during the entire distance of 5.5 km, calculate his average speed in km/h for the Whole journey.
:
Let a = his average speed of the journey
:
Change 20 min to 1/3 hrs
:
Write a time equation; time = dist/speed
1st 3.5 km time + remaining 2km time = total time
+ =
multiply by 15a
15a* + 15a* = 15a
Cancel the denominators and you have
5a + 3a(2) = 15(5.5)
5a + 6a = 82.5
11a = 82.5
a = 82.5/11
a = 7.5 km/hr is the average speed of the whole trip
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