A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is:
Select the correct option: A) 49 B) 4 C) 12 D) 9 E) 27
Let the required number of revolutions made by larger wheel be x.   Then, More cogs, Less revolutions (Indirect Proportion)   14 : 6 :: 21 : x 14 * x = 6 x 21   x =	(6 x 21)/14   x = 9.   Answer is 9.
<result>D</result>
A wheel that has 6 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions mad by the larger wheel is: