An escalator moves towards the top level at the rate of 12 ft.sec and its length is 210 feet. If a person walks on the moving escalator at the rate of 2 feet per second towards the top level, how much time does he take to cover the entire length.  Choose the correct choice from the following:
A) 15 sec B) 10 sec C) 12 sec D) 8 sec E) 9 sec
Time taken to cover the entire length = tot.dist/resultant speed   = 210/ (12+2)= 
<gadget id="calculator">210/ (12+2)</gadget>
<output>15</output>
15 sec   15 secNSWER:15 sec
<result>A</result>
An escalator moves towards the top level at the rate of 12 ft.sec and its length is 210 feet. If a person walks on the moving escalator at the rate of 2 feet per second towards the top level, how much time does he take to cover the entire length.