Let $$t$$ is thickness of the cylinder
$${ r }_{ 1 }$$ is outer radius of the cylinder
$${ r }_{ 2 }$$ is inner radius of the cylinder
$$h$$ is height of the cylinder
$$\therefore t=2 cm$$
$${ r }_{ 1 }=14 cm$$
$$h=70 cm$$
Now, inner radius is calculated as,
$${ r }_{ 2 }={ r }_{ 1 }-t$$
$$\therefore { r }_{ 2 }=14-2=12 cm$$
1) Volume of the hollow cylinder is given by,
$$V=c/s\quad area\times height\quad of\quad cylinder$$
$$\therefore V=\left( \pi { { r }_{ 1 } }^{ 2 }-\pi { { r }_{ 2 } }^{ 2 } \right) \times h$$
$$\therefore V=\pi \left( 14^{ 2 }-12^{ 2 } \right) \times 70$$
$$\therefore V=\frac { 22 }{ 7 } \left( 196-144 \right) \times 70$$
$$\therefore V=22\times 52\times 10$$
$$\therefore V=11440\quad { cm }^{ 3 }$$
2) Given wright of the metal, $$\rho =8\quad \frac { g }{ { cm }^{ 3 } } $$
Let $$m$$ = mass of the cylinder
$$\therefore \rho =\frac { m }{ V } $$
$$\therefore 8=\frac { m }{ 11440 } $$
$$\therefore m=8\times 11440$$
$$\therefore m=91520 gm$$
$$\therefore m=91.520 kg$$