<PRE><B>Question 633104</B>
 A car 15 feet long overtakes a truck 30 feet long which is traveling at 
a rate of 45 miles per hour. 
How fast must the car travel to pass the truck in 3 seconds?
:
The car has to cover the sum of the lengths of the car and the truck (at least)
to pass, which is 45 ft
:
Find the speed required to cover 45 ft in 3 sec, add that to 45 mph
:
45/3 = 15 ft/sec
How fast is that in mph
{{{(3600*15)/5280}}} = 10.227 mph faster than the truck
therefore
45 + 10.227 = 55.227 mph, the speed of the car</PRE>