A train traveled the first d miles of its journey it an average speed of 60 miles per hour, the next...
A train traveled the first d miles of its journey it an average speed of 60 miles per hour, the next d miles of its journey at an average speed of y miles per hour, and the final d miles of its journey at an average speed of 160 miles per hour. If the train’s average speed over the total distance was 90 miles per hour, what is the value of y?
Answer/Solution
110
Steps/Work
Average speed=Total distance traveled /Total time taken
3d/d/60+d/y+d/160=90
Solving for d and y,
15y=11y+480
4y=440
y=110
Answer D
3d/d/60+d/y+d/160=90
Solving for d and y,
15y=11y+480
4y=440
y=110
Answer D