Question 962956
The great runner could travel 10 miles at 5 mph and then run 6 miles at 2 mph. What should be her speed for the next 8 miles so that her overall average speed would be 4 mph.
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let x=travel time for next 8 miles
average speed=total distance/total travel time
total distance=10+6+8=24
total travel time=10/5+6/2+x=5+x
24/(5+x)=4
20+4x=24
4x=4
x=1 hr
her speed for the next 8 miles=8/1=8 mph