A wheel that has 3 cogs is meshed with a larger wheel of 7 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions made by the larger wheel is:  Select
A) 9 B) 10 C) 6 D) 8 E) 7
Explanation :   Let the required number of revolutions made by larger wheel be x.   Then, More cogs, Less revolutions (Indirect Proportion)   7:3::21:x =&gt; 7 * x = 21 * 3   =&gt; x = (21 * 3)/7   =&gt; x = 9   9nswer : 9
<result>A</result>
A wheel that has 3 cogs is meshed with a larger wheel of 7 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions made by the larger wheel is: