<PRE><B>Question 174775</B>
A car went around a one mile track at a speed of 30 miles per hour. At what speed must the car travel on its second time around the track if the driver wants to average 60 miles per hour for the two mile trip? 
---------------------
Time required to go one mile at 30mph:
t = d/r = 1mi/30 mph = (1/30)of an hour = 2 minutes
------------------------
Time required to go two miles at 60 mph:
t = d/r = 2mi/60 mph = (2/60) of an hour = 2 minutes
--------------------
So, for the car to average 60mph it would have to cover the 2 miles in 2 minutes.
But the car has already taken 2 minutes to go 1 mile at 30 mph.
----
So there is no speed that the car can travel on the 2nd mile to average
60 mph for the 2-mile journey.
========================================
Cheers,
Stan H.</PRE>