SOLUTION: The 42km drive from Oakdale to Ridgemont usually takes 28 min. Because highway construction requires a reduced speed limit, the trip now takes 14 min longer. Find the reduced speed

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Question 118715: The 42km drive from Oakdale to Ridgemont usually takes 28 min. Because highway construction requires a reduced speed limit, the trip now takes 14 min longer. Find the reduced speed limit in km/h.
Answer by m.hansen(16) About Me  (Show Source):
You can put this solution on YOUR website!
distance = 42km
time = 28min + 14min = 42min
speed = distance%2Ftime
+speed+=+42km%2F42min+=+1+%28km%2Fmin%29 = 1 km/min
In more usual units of km/hr.
time+=+42min+%281+hr%2F60min%29= .7 hr
+speed+=+%2842km%2F.7hr%29+=+60+%28km%2Fhr%29+ = 60 km/hr