Question

A hemispherical bowl made of iron has inner radius 7 cm. Find the cost of polishing inner hollow portion of bowl at the rate of Rx. 10 per 100 cm^2.

Answer 1

Hemisphere:
r=7cm
Inner CSA of hemisphere=2πr^2
                                           =2·(22/7)·7·7
                                           =308 cm^2
Rate of polishing per 100 cm^2=10/100
Cost of polishing=308·10/100
                            =Rs 30.8

Answer 2

Given:

We have given a hemispherical bowl made of iron has an inner radius of 7 cm.

To Find:

We have to find the  Find cost of polishing the inner hollow portion of the bowl?

Step-by-step explanation:

• We have given the radius of the hemispherical bowl is 7cm.
• Area of the inner portion of the bowl is given by the formula

       $\textrm{ Area of hemisphere}=2\pi r^2$

• We have the radius of hemisphere is 7cm.
• Put the value of radius in the above equation we will get

       $\textrm{ Area of hemisphere}=2\pi (7)^2$

• Also we will put the value of pi in the above equation we get

        $\textrm{ Inner Area of hemisphere}=2\times\frac{22}{7} \times7\times7$

• Now for simplifying the terms we will cancel the terms

        $\textrm{ Inner surface Area of hemisphere}=2\times22 \times7$

• Now multiply the terms we get

        $\textrm{ Inner surface Area of hemisphere}=308$

• Now we have cost for polishing 100 square cm is Rs. 10
• Then cost for polishing 1 square cm will be given by 10 divide 100

• Cost of polishing 308 square cm is given by the

        $\textrm{Cost of polyshing 308}=\frac{10}{100} \times308=30.8$

Hence, the cost is Rs. 30.8