English Medium Class 9 - CBSE Question Bank Solutions for Mathematics

The radius of a spherical balloon increases from 7 cm to 14 cm as air is being pumped into it. Find the ratio of surface areas of the balloon in the two cases.

A hemispherical bowl made of brass has inner diameter 10.5 cm. Find the cost of tin-plating it on the inside at the rate of ₹ 16 per 100 cm².

`["Assume "pi=22/7]`

Find the radius of a sphere whose surface area is 154 cm².

`["Assume "pi=22/7]`

The diameter of the moon is approximately one-fourth of the diameter of the earth. Find the ratio of their surface area.

A hemispherical bowl is made of steel, 0.25 cm thick. The inner radius of the bowl is 5 cm. Find the outer curved surface area of the bowl.

`["Assume "pi = 22/7]`

A right circular cylinder just encloses a sphere of radius r (see figure). Find

1. surface area of the sphere,
2. curved surface area of the cylinder,
3. ratio of the areas obtained in (i) and (ii).

Find the surface area of a sphere of radius 10.5 cm. 

Find the surface area of a sphere of radius 5.6 cm.

Find the surface area of a sphere of radius 14 cm.

Find the surface area of a sphere of diameter 14 cm.

Find the surface area of a sphere of diameter 21 cm.

Find the surface area of a sphere of diameter 3.5 cm.

Find the total surface area of a hemisphere and a solid hemisphere each of radius 10 cm.
(Use 𝜋 = 3.14)

The surface area of a sphere is 5544 `cm^2`, find its diameter.

A hemispherical bowl made of brass has inner diameter 10.5 cm. Find the cost of tin- plating
it on the inside at the rate of Rs. 4 per 100 `cm^2`

The dome of a building is in the form of a hemisphere. Its radius is 63 dm. Find the cost of painting it at the rate of Rs. 2 per sq. m. 

Assuming the earth to be a sphere of radius 6370 km, how many square kilo metres is area
of the land, if three-fourth of the earth’s surface is covered by water?

A cylinder of same height and radius is placed on the top of a hemisphere. Find the curved
surface area of the shape if the length of the shape be 7 cm.

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`.

The diameter of the moon is approximately one fourth of the diameter of the earth. Find the
ratio of their surface areas.