A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 100 kilometers per hour. At what speed, in kilometers per hour, is the car traveling?
Pick.
A) 71.5	B) 72	C) 72.5	D) 73	E) 94.7
Many approaches are possible, one of them:   Let the distance be 1 kilometer.   Time to cover this distance at 100 kilometers per hour is 1/100 hours = 3,600/100 seconds = 36 seconds;   Time to cover this distance at regular speed is 36+2= 
<gadget id="calculator">36+2</gadget>
<output>38</output>
38 seconds= 38/3,600 hours = 4/379 hours;   So, we get that to cover 1 kilometer 1/(4/379) hours is needed --&gt; regular speed 94.7 kilometers per hour (rate is a reciprocal of time or rate=distance/time).   Answer: 94.7.
<result>E</result>
A car traveling at a certain constant speed takes 2 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 100 kilometers per hour. At what speed, in kilometers per hour, is the car traveling?