SOLUTION: A motorist travelled from town X to town Y at an average speed of 90 km/h. after travelling 1/3 of the journey in 45 min. he continued to travel another 120 km to reach town Y. fin

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Question 856040: A motorist travelled from town X to town Y at an average speed of 90 km/h. after travelling 1/3 of the journey in 45 min. he continued to travel another 120 km to reach town Y. find his average speed for the second part of the journey.
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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A motorist travelled from town X to town Y at an average speed of 90 km/h.
after travelling 1/3 of the journey in 45 min. he continued to travel another 120 km to reach town Y.
find his average speed for the second part of the journey.
:
Find the total length of the journey (d)
2%2F3d = 120 km
d = 180 km
:
let s = his speed for last 2/3 of the journey
:
Write a time equation (change 45 min to .75 hrs); time = dist/speed
.75 + 120%2Fs = 180/90
120%2Fs = 2 - .75
120%2Fs = 1.25
s = 120/1.25
s = 96 km/hr for the 2nd half of the journey