Question

A toothed wheel diameter $50cm$ is attached to a smaller wheel of diameter $30cm$. How many revolutions will the smaller wheel make when the larger one makes $15$ revolutions ?

• A. $18$
• B. $20$
• C. $25$
• D. $30$

Answer 1

The correct option is C $25$

Given that diameters of wheels are $50$cm and $30$cm

Distance covered by wheels in $1$ revolution $=50\pi$cm and $30\pi$cm

Let the number of revolutions by smaller wheel be $n$.

Then distance covered by larger wheel in $15$ revolution$=$Distance covered by smaller wheel in $n$ revolutions.

$\Rightarrow 15\times 50\pi =n\times 30\pi$

$\Rightarrow 2n=50$

$\Rightarrow n=25$

Hence the smaller wheel makes $25$ revolutions.