The length of a rectangle is increased by $60 \%$. By what percent would the width have to be decreased to maintain the same area? (in $\%$)

In the given figure,there is a large semicircle with diameter $AB = 56 \ cm$. Inside this,there are four smaller identical semicircles with diameters $AE, EF, FG,$ and $GB$ along the diameter $AB$. $A$ circle is inscribed such that it is tangent to the large semicircle and the two middle smaller semicircles. What is the area (in $cm^2$) of the shaded region?

One of the diagonals of a rhombus is double the other diagonal. Its area is $25\, cm^{2}$. The sum of the diagonals is.......$cm$

$A$ tank is $25 \ m$ long,$12 \ m$ wide and $6 \ m$ deep. The cost of plastering its walls and bottom at $75 \ paise/m^2$ is (in $Rs.$)

In the given figure,if $O$ is the centre of the circle,then find the value of $y$?

$A$ sphere of $30 \ cm$ radius is dropped into a cylindrical vessel of $80 \ cm$ diameter,which is partly filled with water. If its level rises by $x \ cm$,find $x$ (in $cm$). (in $.5$)