SOLUTION: A journey of 540Km is completed in 7 hr. 30 minutes. If 2/3 of the journey is completed at 80 Km/hr. At what speed is the remaining journey completed.

Algebra ->  Finance -> SOLUTION: A journey of 540Km is completed in 7 hr. 30 minutes. If 2/3 of the journey is completed at 80 Km/hr. At what speed is the remaining journey completed.      Log On


   



Question 957366: A journey of 540Km is completed in 7 hr. 30 minutes. If 2/3 of the journey is completed at 80 Km/hr. At what speed is the remaining journey completed.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
You can put this solution on YOUR website!
A journey of 540Km is completed in 7 hr. 30 minutes.
If 2/3 of the journey is completed at 80 Km/hr.
At what speed is the remaining journey completed.
:
Let s = the av speed the last third of the journey
:
2%2F3* 540 = 360 km at 80 km/h
then
1%2F3 * 540 = 180 km at s km/hr
:
Write a time equation, time = dist/speed
;
80km/h time + s km/h time = total time (7.5 hrs)
360%2F80 + 180%2Fs = 7.5
4.5 + 180%2Fs = 7.5
180%2Fs = 7.5 - 4.5
180%2Fs = 3
180 = 3s
s = 180/3
s = 60 km/hr for the remainder of the journey