If a drilling rig operates $10$ hours a day and takes $40$ hours to drill $8$ meters of earth's surface, the productivity of the drilling rig will be

$2\mathrm{.}0$ meters per day

$0\mathrm{.}8$ meters per day

$1\mathrm{.}0$ meter per day

$0\mathrm{.}4$ meters per $d$