A Caterpillar crawls a distance with speed of 21inches/min in the one direction and after feeding moves back in the same direction with 7inches/min and what is the average speed of it?	Choose the correct choice from the following answers:
A) 11.5 inch/ min B) 10.5 inch/ min C) 12.5 inch/ min D) 13.5 inch/ min E) 14.5 inch/ min
average speed = 2*21*7/(21+7) = 2*21*7/28 = 21/2= 
<gadget id="calculator">21/2</gadget>
<output>21/2 = around 10.5</output>
10.5 inch/ min   ANSWER:10.5 inch/ min
<result>B</result>
A Caterpillar crawls a distance with speed of 21inches/min in the one direction and after feeding moves back in the same direction with 7inches/min and what is the average speed of it?