<PRE><B>Question 957366</B>
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
:
{{{2/3}}}* 540 = 360 km at 80 km/h
then
{{{1/3}}} * 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)
{{{360/80}}} + {{{180/s}}} = 7.5
4.5 + {{{180/s}}} = 7.5
{{{180/s}}} = 7.5 - 4.5
{{{180/s}}} = 3
180 = 3s
s = 180/3
s = 60 km/hr for the remainder of the journey 
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