Seven equal cubes each of side $5 \, cm$ are joined end to end. Find the surface area of the resulting cuboid? (in $cm^2$)

In $\triangle ABC$,$\angle A = 90^{\circ}$ and $AD \perp BC$,where $D$ lies on $BC$. If $BC = 8 \ cm$ and $AC = 6 \ cm$,then the ratio of the area of $\triangle ABC$ to the area of $\triangle ACD$ is:

$A$ wire which when bent in the form of a square encloses an area of $484 \, cm^2$. What will be the enclosed area when the same wire is bent into the form of a circle? (in $cm^2$)

If the length of one side and the diagonal of a rectangle are $7 \text{ cm}$ and $25 \text{ cm}$ respectively,then find its perimeter (in $\text{cm}$).

Find the number of bricks,each measuring $25\, cm \times 12.5\, cm \times 7.5\, cm$,required to construct a wall $12\, m$ long,$5\, m$ high,and $0.25\, m$ thick,if the sand and cement mixture occupies $5\%$ of the total volume of the wall.

In trapezium $ABCD$,$AB || CD$ and $AB = 2 \, CD$. Its diagonals intersect at $O$. If the area of $\Delta AOB = 84 \, cm^2$,then the area of $\Delta COD$ is equal to (in $cm^2$)