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?  Pick one:
A) 68	B) 84	C) 90	D) 110	E) 135
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 110
<result>D</result>
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?