Question

The radius of a circular pond is 7 m. What will be the total cost to pave a circular path of width 7m around the pond at the rate of Rs.10 per $m^2$

• A. Rs. 4620
• B. Rs. 2840
• C. Rs. 2110
• D. Rs. 3250

Answer 1

The correct option is A Rs. 4620

As you can see, the pathway around the pond forms an outer circle with radius 14 m.
$\therefore$ Area of the pathway = π( $R^2$ - $r^2$ )
Here, R =14 m and r = 7 m
$\therefore$π( $R^2$ - $r^2$ ) =$\frac{22}{7}$( ${14}^2$ - $7^2$ )
= $\frac{22}{7}(196-49)$
=$\frac{22}{7}\times 147$
=$22\times 21$
=$462m^2$
$\therefore$ Total cost = $462\times 10$ = Rs. 4620