Rachel,an engineering student,was asked to make a model shaped like a cylinder with two cones attached at its two ends by using a thin aluminium sheet. The diameter of the model is $3\, cm$ and its total length is $12\, cm$. If each cone has a height of $2\, cm$,find the volume of air contained in the model that Rachel made. (Assume the outer and inner dimensions of the model to be nearly the same.) Unless stated otherwise,take $\pi = \frac{22}{7}$. (in $cm^3$)

Hanumappa and his wife Gangamma are busy making jaggery out of sugarcane juice. They have processed the sugarcane juice to make the molasses,which is poured into moulds in the shape of a frustum of a cone having the diameters of its two circular faces as $30 \,cm$ and $35 \,cm$ and the vertical height of the mould is $14 \,cm$ (see figure). If each $cm^3$ of molasses has a mass of about $1.2 \,g$,find the mass of the molasses that can be poured into each mould (in $kg$). [Take $\pi = \frac{22}{7}$]

How many silver coins,$1.75 \,cm$ in diameter and of thickness $2 \,mm$,must be melted to form a cuboid of dimensions $5.5 \,cm \times 10 \,cm \times 3.5 \,cm$? [Take $\pi = \frac{22}{7}$]

$A$ medicine capsule is in the shape of a cylinder with two hemispheres stuck to each of its ends (see figure). The length of the entire capsule is $14 \, mm$ and the diameter of the capsule is $5 \, mm$. Find its surface area. $\left[ \text{Use } \pi = \frac{22}{7} \right]$ (in $mm^2$)

$A$ cone of height $24\, cm$ and radius of base $6\, cm$ is made up of modelling clay. $A$ child reshapes it in the form of a sphere. Find the radius of the sphere (in $cm$).

The decorative block shown in the figure is made of two solids - a cube and a hemisphere. The base of the block is a cube with edge $5 \, cm$,and the hemisphere fixed on the top has a diameter of $4.2 \, cm$. Find the total surface area of the block. (in $cm^2$) (Take $\pi = \frac{22}{7}$)