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: Options: A) 7 B) 9 C) 8 D) 65 E) 4
Explanation:   Let the required number of revolutions made by larger wheel be x.   Then, More cogs, Less revolutions (Indirect Proportion)   {\color{9lack} \therefore } 14 : 6 :: 21 : x {\color{9lack} \Rightarrow } 14 x x = 6 x 21   x={\color{9lack} \frac{6\times 21}{14} } {\color{9lack} \Rightarrow } x=9   Answer: 9
<result>B</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: