**.**

**NCERT Solutions for Class 8 Maths Chapter 9 ****Mensuration**** Ex 9.3**

**Ex 9.3 Class 8 Maths Question 1.**

### Given a cylindrical tank, in which situation will you find the surface area and in which situation volume.

(a) To find how much it can hold.

(b) Number of cement bags required to plaster it.

(c) To find the number of smaller tanks that can be filled with water from it.

**Solution:**(a) In this situation, we can find the volume.

(b) In this situation, we can find the surface area.

(c) In this situation, we can find the volume.

**Ex ****9.3**** Class 8 Maths Question 2.**

### Diameter of cylinder A is 7 cm, and the height is 14 cm. Diameter of cylinder B is 14 cm and height is 7 cm. Without doing any calculations can you suggest whose volume is greater? Verify it by finding the volume of both the cylinders. Check whether the cylinder with greater volume also has greater surface area?

**Solution:**

Cylinder B has a greater volume.

**Verification:**

Volume of cylinder A = Ï€r^{2}h

**Ex ****9.3**** Class 8 Maths Question 3.**

### Find the height of a cuboid whose base area is 180 cm^{2} and volume is 900 cm^{3}.

**Solution:**Given: Base area of the cuboid = lb = 180 cm

^{2}

Volume of the cuboid = 900 cm

^{3}

Volume of a cuboid = l × b × h

900 = 180 × h

h = 5 cm

Hence, the height of the cuboid is 5 cm.

**Ex ****9.3**** Class 8 Maths Question 4.**

### A cuboid is of dimensions 60 cm × 54 cm × 30 cm. How many small cubes with side 6 cm can be placed in the given cuboid?

**Solution:**Volume of a cuboid = l × b × h = 60 cm × 54 cm × 30 cm = 97200 cm

^{3}

Volume of a cube = (Side)

^{3}= (6)

^{3}= 216 cm

^{3}

Number of the cubes placed in the cuboid

**Ex ****9.3**** Class 8 Maths Question 5.**

### Find the height of the cylinder whose volume is 1.54 m^{3} and the diameter of the base is 140 cm.

**Solution:**Volume of the cylinder = 1.54 m

^{3}

Diameter of the base = 140 cm = 1.4 m

Volume of a cylinder = Ï€r^{2}h

**Ex ****9.3**** Class 8 Maths Question 6.**

### A milk tank is in the form of a cylinder whose radius is 1.5 m and length is 7 m. Find the quantity of milk in litres that can be stored in the tank.

**Solution:**

Here, radius of the tank = 1.5 m

Height of the tank = 7 m

Volume of the milk tank = Ï€r^{2}h

= 22/7 × 1.5 × 1.5 × 7

= 22 × 2.25

= 49.50 m^{3}

Quantity of milk in litres = 49.50 × 1000 L (∵ 1 m^{3} = 1000 litres)

= 49500 L

Hence, the required quantity of milk is 49500 L.

**Ex ****9.3**** Class 8 Maths Question 7.**

### If each edge of a cube is doubled,

(i) how many times will its surface area increase?

(ii) how many times will its volume increase?

**Solution:**Let each edge of the cube be x cm.

If the edge is doubled, then the new edge = 2x cm

(i) Original surface area of the cube = 6x

^{2}cm

^{2}

New surface area of the cube = 6(2x)

^{2}= 6 × 4x

^{2}= 24x

^{2}

Ratio = 6x

^{2}: 24x

^{2}= 1 : 4

Hence, the new surface area will be four times the original surface area.

(ii) Original volume of the cube = x^{3} cm^{3}

New volume of the cube = (2x)^{3} = 8x^{3} cm^{3}

Ratio = x^{3} : 8x^{3} = 1 : 8

Hence, the new volume will be eight times the original volume.

**Ex ****9.3**** Class 8 Maths Question 8.**

### Water is pouring into a cuboidal reservoir at the rate of 60 litres per minute. If the volume of the reservoir is 108 m^{3}, find the number of hours it will take to fill the reservoir.

**Solution:**Volume of the reservoir = 108 m

^{3}= 108000 L [∵ 1 m

^{3}= 1000 L]

Volume of water flowing into the reservoir in 1 minute = 60 L

Time taken to fill the reservoir

**Related Links:**

**NCERT Solutions for Maths Class 9**

**NCERT Solutions for Maths Class 10**

**NCERT Solutions for Maths Class 11**