**GSEB Solutions for Class 8 Mathematics – Area and volume of cylinder ****(English Medium)**

GSEB SolutionsMathsScience

**Exercise**

**Solution 1:**

Diameter (d) of the cylindrical tin = 80 cm = 0.8 m

Thus, the radius (r) of the cylindrical tin = 0.4 m

Height (h) of the cylindrical tin = 1.5 m

Curved surface area of the cylindrical tin = 2πrh

= 2 × 3.14 × 0.4 × 1.5

= 3.768 m^{2}

Thus, the curved surface area of the cylindrical tin is 3.768 m^{2}.

**Solution 2:**

**Solution 3:**

**Solution 4:**

**Solution 5:**

**Solution 6:**

**Solution 7:**

**Practice 1**

**Solution 1:**

**Solution 2:**

**Solution 3:**

**Solution 4:**

Radius (r) of the cylinder = 20 cm

Height (h) of the cylinder = 30 cm

Curved surface area of the cylinder = 2πrh

= 2 × 3.14 × 20 × 30

= 3768 cm^{2}

Thus, the curved surface area of the cylinder is 3768 cm^{2}.

**Solution 5:**

**Practice 2**

**Solution 1:**

**Solution 2:**

**Solution 3:**

**Solution 4:**

For the given cylindrical chimney,

Diameter d = 80 cm = 0.80 m and height h = 12.5 m.

Curved surface area of the cylindrical chimney

= πdh

= 3.14 × 0.80 × 12.5

= 31.4 m^{2}

Cost of painting 1 m^{2} area = Rs. 140

∴ Cost of painting 31.4 m^{2} area = Rs. (140 × 31.4)

= Rs. 4,396

Thus, the cost of painting the chimney from outside is Rs. 4,396.

**Solution 5:**

**Solution 6:**

**Practice 3**

**Solution 1:**

**Solution 2:**

**Solution 3:**

**Solution 4:**

**Solution 5:**

For the cylinder tank of milk,

Radius (r) = 25 cm and height (h) = 2 m = 200 cm

Volume of the milk stored in the cylindrical tank

= Volume of the cylinder

= πr^{2}h

= 3.14 × 25 × 25 × 200

= 3,92,500 cm^{3}

Now, 1 cm^{3} = 1 ml

∴ 3,92,500 cm^{3} = 3,92,500 ml

Thus, the volume of the milk in the tank is 3,92,500 ml.

Number of bags filled with 500 ml of milk = 1

**Solution 6:**