Question 704483
roselinda rode her bike for 60 miles at 30 miles per hour and then rode 20 miles at 10 miles per hour. how fast would she have to ride for the next 20 miles to have an overall average speed of 20 miles per hour for the entire trip?
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let x=speed required for an overall average speed of 20 mph
Speed=distance/travel time
Total distance=60+20+20=100 miles
Total travel time=60/30+20/10+20/x=2+2+20/x=4+20/x=(4x+20)/x
distance/travel time=100/(4x+20)/x=20
100x/(4x+20)=20
80x+400=100x
20x=400
x=20
speed required for an overall average speed of 20 mph=20 mph