$\"\"$

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Volume of the hemispherical is $\"\"$ cubic centimeter.

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The volume of the solid is $\"\"$ .

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$\"\"$

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$\"\"$

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Surface area of the solid $\"\"$ .

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$\"\"$ .

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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Find the minimised cost :

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$\"\"$

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Differentiate on each side with respect to $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

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$\"\"$

\

$\"\"$

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$\"\"$

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Substitute $\"\"$ in $\"\"$ .

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$\"\"$

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$\"\"$

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$\"\"$ .

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The minimum cost of tank dimension is $\"\"$ and $\"\"$ $\"\"$

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The minimum cost of tank dimension is $\"\"$ and $\"\"$ .