Question

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 rev.olutions made by the larger wheel is

• A. 4
• B. 9
• C. 12
• D. 49

Answer 1

The correct option is B 9

Let the bigger wheel make $x$ revolutions.

Now, the number of cogs is inversely proportional to the number of revolution of a wheel.

$\therefore 6\times 14=x\times 21⟹x=\frac{6\times 21}{14}⟹x=9$.

So, the bigger wheel will make 9 revolutions by the time the smaller one makes 14 revolutions.