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Volumes Practice Test 4

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Question : 3 of 16

Marks: +1, -0

Diameter of a roller is 2.4 m and it is 1.68 m long. If it takes 1000 complete revolutions once over to level a field, the area of the field is

12672 sq. m
12671 sq. m
12762 sq. m
11768 sq. m

Solution:

Concept:

The area levelled in one revolution equals the curved surface area of the cylindrical roller,

2\pi rh

.

Explanation:

Diameter

= 2.4

m, so radius

r = 1.2

m.

Length of roller

h = 1.68

m.

Curved surface area in one revolution:

2\pi rh = 2 \times \frac{22}{7} \times 1.2 \times 1.68

= 12.672 \text{ sq. m}

Area levelled in

1000

revolutions:

12.672 \times 1000 = 12672 \text{ sq. m}

Answer:

The area of the field is

\boxed{12672 \text{ sq. m}}

.

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