A wheel that has 12 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions made by the larger wheel is:  Choose the correct answer:	A) 9	B) 10	C) 6	D) 18	E) 7
Explanation :   Let the required number of revolutions made by larger wheel be x.   Then, More cogs, Less revolutions (Indirect Proportion)   14:12::21:x =&gt; 14 * x = 21 * 12   =&gt; x = (21 * 12)/14   =&gt; x = 18   Answer : 18
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A wheel that has 12 cogs is meshed with a larger wheel of 14 cogs. When the smaller wheel has made 21 revolutions, then the number of revolutions made by the larger wheel is: