Question

There are two concentric circles. The radii of the two circles are $100m$ and $110m$ respectively. A wheel of radius $30cm$ rolls on the smaller circle and another wheel rolls on the larger circle. After they have completed one revolution, it is found that the two wheels rolled equal number of times on their respective axes. What is the radius of the other wheel?

• A. $31cm$
• B. $32cm$
• C. $33cm$
• D. $34cm$

Answer 1

The correct option is C $33cm$

Let the radius be $R$.
$\frac{2\pi \times 100}{2\pi \times 30}=\frac{2\pi \times 100}{2\pi \times R}$R = 33\ cm$.