A breathalyzer is a portable electrochemical instrument that measures the concentration of ethyl alcohol in a sample of exhaled breath. A forensic chemist checks the calibration of a breathalyzer by testing a standard air sample known to contain $0\mathrm{.}177$ mg$/$L

of ethanol seven times. The average value of these seven replicate measurements is found to be $0\mathrm{.}141$ mg$/$L

$.$