Total surface area of a hemisphere $= \dots$

Find the volume of a hemisphere with a diameter of $12 \, cm$. (Use $\pi = 3.14$) (in $cm^3$) (in $.16$)

$A$ cone is $8.4 \, cm$ high and the radius of its base is $2.1 \, cm$. It is melted and recast into a sphere. The radius of the sphere is (in $cm$):

$A$ room without a ceiling is $12 \, m$ long,$4 \, m$ wide,and $3 \, m$ high. Find the length of the longest rod that can be placed in that room. (in $m$)

$A$ metal sphere of radius $20\, cm$ is melted and then cast into small hemispheres each of radius $5\, cm$. Find the number of hemispheres thus obtained (in balls).

The radius and slant height of a conical vessel are $35 \,cm$ and $91 \,cm$ respectively. What is its capacity in litres (in $.8$)?