Question

A wooden toy is in the form of a cone surmounted on a hemisphere. The diameter of the base
of the cone is 16 cm and its height is 15 cm. Find the cost of painting the toy at Rs. 7 per 100
`cm^2`.

Answer 1

Diameter of cone = 16cm.
∴ Radius of cone = 8cm.
Height of cone = 15cm
Slant height of cone - `sqrt(8^2+15^2)`

-`sqrt(64+225)`

-`sqrt(289)`

-17 cm 

∴ Total curved surface area of toy

-πrl + `2πr^2`

-`22/7 × 8 × 17 + 2 × 22/7 × 8^2`

- `5808/7cm^2`

Now .cost of `100cm^2 - Rs.7`

`1cm^2 - Rs7/100`

Hence , cost of `5808/7 cm^2 - Rs (5808/7×7/100)`

-Rs.58.08.

Answer 2

Diameter of cone = 16cm.
∴ Radius of cone = 8cm.
Height of cone = 15cm
Slant height of cone - `sqrt(8^2+15^2)`

-`sqrt(64+225)`

-`sqrt(289)`

-17 cm 

∴ Total curved surface area of toy

-πrl + `2πr^2`

-`22/7 × 8 × 17 + 2 × 22/7 × 8^2`

- `5808/7cm^2`

Now .cost of `100cm^2 - Rs.7`

`1cm^2 - Rs7/100`

Hence , cost of `5808/7 cm^2 - Rs (5808/7×7/100)`

-Rs.58.08.