Question

A piece of land is $100$ metres $\times$ $21$ metres. A semi-circular plot has been added on one side of its breadth. How long will it take a man to walk round it at the rate of $3.6$ kilometres per hour?

Answer 1

Perimeter of the plot $=$ three sides of rectangle $+$ semi-circumference
$(100+100+21)+\frac{1}{2}\times 2\pi r=221m+\frac{22}{7}\times \frac{21}{2}m$
$=254m$
Time to walk $3.6km$ i.e., $3600m=60$ minutes
$\therefore$ Time to walk $254$ metres
$==\frac{60}{3600}\times 254$ minutes
$4$ minutes $14$ sec