$4.$The temperature in a chemical reactor was measured every half hour under the same conditions, using two different devices. The results were as follows:

$\backslash$table$[[$Device $1$:$,78\mathrm{.}1C,79\mathrm{.}2C,78\mathrm{.}9C,80\mathrm{.}2C,78\mathrm{.}3C,78\mathrm{.}8C,79\mathrm{.}4C$