Question

The largest hand of a clock is $42$ $cm$ long, then the distance covered by the extremity in $20$ $min$ is

• A. $88$ $cm$
• B. $80$ $cm$
• C. $82$ $cm$
• D. $84$ $cm$

Answer 1

The correct option is A $88$ $cm$

Radius$=42$cm

In $20$ minutes, the hand travels $20\times 6$

$={120}^o$

Distance travelled $=\frac{\theta }{360}\times 2\pi r$

$=\frac{120}{360}\times 2\times \frac{22}{7}\times 42$

$=\frac{2}{3}\times 22\times 6$

$=44\times 2=88$cm.