A thin metal rod expands $1\mathrm{.}9$ mmmm when its temperature is increased by $2\mathrm{.}0$C$$C$.$ If an identical rod of the same material, except twice as long, also has its temperature increased by $2\mathrm{.}0$C$$C$,$ it will expand

$7\mathrm{.}6$ mmmm$\mathrm{.}3\mathrm{.}8$ mmmm$\mathrm{.}1\mathrm{.}9$ mmmm$\mathrm{.}0\mathrm{.}95$ mmmm$.$