SOLUTION: On his way from suburb A to suburb B, the bus driver maintained a speed of 44 km/h. When he arrived at B, he found out that he needed to hurry to be back at A in time. So he drove

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Question 895063: On his way from suburb A to suburb B, the bus driver maintained a speed of 44 km/h. When he arrived at B, he found out that he needed to hurry to be back at A in time. So he drove the bus at a constant speed of 66 km/h on his way back along the same route. What speed did he need to keep constant during the whole trip so that it would take the same time?
Answer by ankor@dixie-net.com(22740) (Show Source):
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On his way from suburb A to suburb B, the bus driver maintained a speed of 44 km/h.
When he arrived at B, he found out that he needed to hurry to be back at A in time.
So he drove the bus at a constant speed of 66 km/h on his way back along the same route.
What speed did he need to keep constant during the whole trip so that it would take the same time?
:
Let d = the one-way dist form A to B
let a = the average speed for the round trip
write a time equation, time = dist/speed
+ =
multiply equation by 132a, cancel the denominators and you have:
3ad + 2ad = 132(2d)
5ad = 264d
divide both sides by d
5a = 264
a = 265/5
a = 52.8 km/h for the whole trip will take the same time