If each edge of a cube is increased by $50 \%$,the percentage increase in its surface area is (in $\%$)

If three metallic spheres of radii $6\, cm$,$8\, cm$,and $10\, cm$ are melted to form a single sphere,the diameter of the new sphere will be (in $cm$)?

How many bricks,each measuring $250\, cm$ by $12.5\, cm$ by $7.5\, cm$,will be required to build a $5\, m$ long,$3\, m$ high and $20\, cm$ thick wall?

Water is flowing at the rate of $5 \text{ km/h}$ through a pipe of diameter $14 \text{ cm}$ into a rectangular tank which is $50 \text{ m}$ long and $44 \text{ m}$ wide. The time taken,in hours,for the rise in the level of water in the tank to be $7 \text{ cm}$ is:

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

If the volumes of two cubes are in the ratio $27: 1$,the ratio of their edges is