The radius of the base of a hollow cone is $8\, cm$ and its height is $15\, cm$. $A$ sphere of the largest possible radius is placed inside the cone. What is the ratio of the radius of the base of the cone to the radius of the sphere?

$A$ hollow hemispherical bowl is made of silver with its outer radius $8\, cm$ and inner radius $4\, cm$. The bowl is melted to form a solid right circular cone of radius $8\, cm$. The height of the cone formed is......$cm$

The number of bricks,each measuring $25\,cm \times 12.5\,cm \times 7.5\,cm$,required to construct a wall $6\,m$ long,$5\,m$ high,and $0.5\,m$ thick,if the mortar occupies $5\%$ of the volume of the wall,is:

$A$ right circular cone is exactly fitted inside a cube in such a way that the edges of the base of the cone are touching the edges of one of the faces of the cube and the vertex is on the opposite face of the cube. If the volume of the cube is $343 \, c.c.$,then what approximately is the volume of the cone? (in $c.c.$)

$2\, cm$ of rain has fallen on a $1\, km^2$ of land. Assuming that $50\%$ of the raindrops could have been collected and contained in a pool having a $100\, m \times 10\, m$ base,by what level would the water level in the pool have increased? (in $m$)

If the diameter of a sphere is decreased by $25 \%$,its curved surface area will be decreased by (in $\%$).