Question

Answer the question in attachment...​

Answer 1

Answer:

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Answer 2

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${\bigstar {\boxed{\red{\bf{Given:-}}}}}$

• Diameter = 7mm

• Radius = $\displaystyle\frac {7}{2}mm=\displaystyle\frac {7}{2000}m$

• Height= $\displaystyle\frac {20}{100}m$

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${\bigstar {\boxed{\red{\bf{Find:-}}}}}$

• The amount spent on coating 1000 packets of pencils = ?

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${\bigstar {\boxed{\red{\bf{Solution:-}}}}}$

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• Pencil if a solid with a cylinder and a cone surmounted on it.

But as we need to find it's CSA,

1 packet = 10 pencils

1000packets = 10,000 pencils

Now,

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CSA of pencil = CSA of cylinder

∴CSA of pencil = 2πrh

=$2×\displaystyle\frac {22}{7}×\displaystyle\frac {7}{2000}×\displaystyle\frac {20}{100}×10×1000$

= 22 × 2

= 44m²

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Cost of the pencils

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Rate of per m² = Rs.400

Rate of per 44m²

= 400 × 44

= Rs. 17600

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The amount spent on coating 1000 packets of pencils = Rs.17600.

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