Question

Find the cost of polishing a circular table-top of radius 7 m, if the rate of polishing is ₹10/��2.

Answer 1

Before, finding the answer. Lest find out on how we can find the answer.

• First, we must find the area of the circular table top by using the formula of :

$\boxed{\pi r ^{2} }$

• Then, we must multiply the area of Circular table top with the rate.

_____________________

Given :

• Radius = 7 m
• Rate = Rs. 10

To find :

The rate of polishing.

Formula Used :

πr²

Solution :

We know that,

Area of Circle = πr²

Where,

π = 22/7.

Area of Circular Top = πr²

$\sf = \dfrac{22}{7} \times {radius}^{2}$

$\sf = \dfrac{22}{7} \times {7}^{2}$

$\sf = \dfrac{22}{7} \times 49$

$\sf = \dfrac{1078}{7}$

$\sf = 134.75 \: {m}^{2}$

Hence, the Area of Circular region is 134.75 m².

Rate of Polishing = Area × rate

= 134.75 × 10

= ₹ 1347.5

Hence, the Rate of Polishing is ₹ 1347.5.