0

Mensuration - III (Level : Moderate)

Attempted 0/15 Correct 0 Score 0

Find the ratio of the volumes of a right circular cylinder and a right circular cone of the same base if the height of the cylinder is twice the height of the cone.

  1. 1 : 3

  2. 2 : 3

  3. 3 : 2

  4. 6 : 1

  5. None of these


Correct Option: D
Explanation:

Volume of cylinder/volume of cone = (π*r2*2h)/[(1/3)πr2h)]

= 6/1

= 6 : 1

Find the volume of a spherical shell whose external and internal radii are 6 cm and 4 cm, respectively.

  1. 304π/3 cm3

  2. 154π cm3

  3. 606π cm3

  4. 608π/3 cm3

  5. None of these


Correct Option: D
Explanation:

Volume of a spherical shell = 4π/3 (R3 – r3)

= 4π/3 (63 - 43)

= 4π/3(152)

= 608π/3 cm3

Find the volume of a pyramid of base area 30 cm2 and height 8 cm.

  1. 80 cm3

  2. 100 cm3

  3. 90 cm3

  4. 110 cm3

  5. None of these


Correct Option: A
Explanation:

Volume of a pyramid = 1/3 * base area * height = 1/3*30*8 = 80 cm3

If the height and radius of a right circular cylinder become thrice, then the volume of the cylinder will become

  1. 18 times

  2. 15 times

  3. 30 times

  4. 27 times

  5. None of these


Correct Option: D
Explanation:

Original volume of the cylinder = πr2h

New radius = 3r and new height = 3h

So, new volume = π(3r)2(3h) = 27πr2h

So, the volume will become 27 times of the original volume.

The radius and height of a right circular cone are in the ratio 5 : 7. If its volume is 4950 m3, find its slant height.

  1. 26 m

  2. 20 m

  3. 30.88 m

  4. 20.88 m

  5. None of these


Correct Option: C
Explanation:

Let r = 5x m and h = 7x m Volume of the cone = 4950 m3
1/3 × π × (5x)2 × (7x) = 4950 x = 3 So, r = 15 m and h = 21 m  So, l = √l2 + h2 = √954 = 30.88 m

The base of a right pyramid is a square and length of diagonal of the base is 6√2 m. If the volume of the pyramid is 120 m3, find its height.

  1. 12 m

  2. 8 m

  3. 10 m

  4. 9 m

  5. None of these


Correct Option: C
Explanation:

Area of the base = 1/2*(diagonal)2

1/2*6√2*6√2 = 36 m2

So, volume of the pyramid = 1/3*height*area of base

120 = 1/3*h*576

h = 10 m

A sphere and a cylinder have equal radii of their bases as 7 cm. If their curved surface areas are in the ratio 2 : 7, then find the ratio of radius and height of the cylinder.

  1. 1 : 7

  2. 1 : 3

  3. 2 : 3

  4. 3 : 4

  5. None of these


Correct Option: A
Explanation:

Curved surface area of sphere/Curved surface area of cylinder = 2/7

4πr2/2πrh = 2/7

2r/h = 2/7

h = 49

Now, the ratio of radius and height of the cylinder = 7/49 = 1 : 7

A metallic sphere of radius 9 cm is melted and recast into a cylinder, whose height is 12 cm. What is the radius of the cylinder?

  1. 9 cm

  2. 18 cm

  3. 21 cm

  4. 15 cm

  5. None of these


Correct Option: A
Explanation:

As volume of the cylinder is equal to the volume of the sphere,

πr2 × 12 = 4/3π93

r2 x 12 = (4 x 9 x 9 x 9)/3

r = 9 cm

The length, breadth and height of a cuboid are 12 m, 6 m and 5 m, respectively. The cuboid is melted and converted into 10 equal cubes. In this process, 25% of the material is lost. How long will be the edge of each cube?

  1. 2 m

  2. 3 m

  3. 4 m

  4. 6 m

  5. None of these


Correct Option: B
Explanation:

Volume of cuboid = 12*6*5 = 360 m3

Material lost = 25% of 360 = 90 m3

So, the remaining material = 360 – 90 = 270 m3

Now, the volume of each cube = 270/10 = 27 m3

So, a3 = 27

a = 3 m

So, the edge of each cube is 3 m.

A cube of side 2 m length is cut into small cubes of side 25 cm each. How many such small cubes can be obtained?

  1. 500

  2. 512

  3. 510

  4. 576

  5. None of these


Correct Option: B
Explanation:

Number of small cubes = Volume of bigger cube/Volume of each smaller cube 

= (200 x 200 x 200)/(25 x 25 x 25)

= 512 cubes

Three cubes of sides 7 cm each are kept adjacent to each other. What is the total surface area of the cuboid formed?

  1. 484 cm2

  2. 441 cm2

  3. 343 cm2

  4. 686 cm2

  5. None of these


Correct Option: D
Explanation:

Because 3 cubes are adjacently joined, length of cube = 7 + 7 + 7 = 21 cm, breadth = 7 cm and height = 7 cm. 

Total surface area = 2(lb + bh + hl) = 2(21 x 7 + 7 x 7 + 7 x 21) 

= 686 cm2

When a cubical metallic piece of edge 5 cm is dropped in a cylindrical glass of water, the water column rises by 4 cm. What is the radius of the base of the glass?

  1. 6√6/2√π cm

  2. 4√5/2√π cm

  3. 5√5/2√π cm

  4. 3√5/2√π cm

  5. None of these


Correct Option: C
Explanation:

Volume of the cubical metallic piece = volume of the water column = 5*5*5 = π*r2*4

= π (r2)(4) = 5*5*5

r = 5√5/2√π cm

A road roller is in the shape of a cylinder. The radius of cross-section is 10.5 cm and the length is 1.5 m. What is the area covered by the roller in making 100 revolutions?

  1. 100 m2

  2. 99 m2

  3. 84 m2

  4. 75 m2

  5. None of these


Correct Option: B
Explanation:

The area covered by the road roller in one revolution is its curved surface area.

So, area covered in 100 revolutions = 100 * 2πrh 

= (100 * 2 * 22 *10.5*1.5)/(7*100) 

= 99 m2

The volume of a right circular cone is 480π cm3. If the area of its base is 144π cm2, what is the vertical height of the cone?

  1. 10 cm

  2. 12 cm

  3. 14 cm

  4. 16 cm

  5. None of these


Correct Option: A
Explanation:

Volume of the cone = 480π cm3

1/3*π*r2*h = 480π

Now, it is given that area of base(πr2) = 144π cm2

So, 1/3*144π*h = 480π

h = 10 cm

The diameter of the base of a cylinder is 21 cm and its height is 20 cm. What is the volume of the cylinder?

  1. 6530 cm3

  2. 6930 cm3

  3. 5930 cm3

  4. 4930 cm3

  5. None of these


Correct Option: B
Explanation:

Volume of the cylinder = πr2

= 22/7*21/2*21/2*20 

= 6930 cm3

- Hide questions