SOLUTION: During the first 20km of a 50 km bicycle race, Rosa's average speed was 30 km/h. What must her average speed be during the remainder of the race if she is to finish the race in les

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Question 908918: During the first 20km of a 50 km bicycle race, Rosa's average speed was 30 km/h. What must her average speed be during the remainder of the race if she is to finish the race in less than 1.5 h?
Answer by lwsshak3(11628) About Me  (Show Source):
You can put this solution on YOUR website!
During the first 20km of a 50 km bicycle race, Rosa's average speed was 30 km/h. What must her average speed be during the remainder of the race if she is to finish the race in less than 1.5 h?
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travel time=distance/speed
let x=average speed during the remainder of the race
20/30+30/x=1.5
30/x=1.5-20/30
30/x=3/2-2/3=9/6-4/6=5/6
x/30=6/5
x=36
What must her average speed be during the remainder of the race? >36 km/hr