SOLUTION: Having travelled halfway to the end of a journey at an average speed of 15km/hr, how fast must you traverse the rest of the trip on order to average 20 km/hr?
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-> SOLUTION: Having travelled halfway to the end of a journey at an average speed of 15km/hr, how fast must you traverse the rest of the trip on order to average 20 km/hr?
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Question 793164: Having travelled halfway to the end of a journey at an average speed of 15km/hr, how fast must you traverse the rest of the trip on order to average 20 km/hr?
How do I do this? I know that simply averaging the two speeds would be incorrect. Answer by mananth(16946) (Show Source):
You can put this solution on YOUR website! Let y be the rate in second half and x the total distance
t=d/r
time first half + time second half = time for total journey
(x/2)/(15)+ (x/2) /y = x/20
x/30 -x/20 = - x/2y
(2x-3x)/60 = -x/2y
-x/60 = -x/2y
2y=60
y=30 km/h
