Question

A circular grassy plot of land $42$ m is diameter has a path $3.5$ m wide running round its outside. Find the cost of gravelling the path at Rs. $4$ per square metre.

• A. Rs. $2002$
• B. Rs. $2003$
• C. Rs. $2011$
• D. Rs. $2000$

Answer 1

The correct option is A Rs. $2002$

Radius of the circular path $=$ $21$ cm
Radius of the outer circle $=$ $24.5$ cm
The area of the ring $=$ $\pi R^2-\pi r^2$

$=\pi ({24.5}^2-{21}^2)$

$=\pi \left(159.25\right)$

$=\frac{22}{7}\times 159.25$

$=500.5{\text{cm}}^2$

Cost of gravelling the path is $500.5\ast 4=$ Rs. $2002.$