## Elementary Statistics (12th Edition)

If a value is unusual, then it is more than two standard deviations far from the mean. $Minimum \ usual \ value=mean-2\cdot(standard \ deviation)=0.8241-2\cdot0.0057=0.8127$ $Maximum \ usual \ value=mean+2\cdot(standard \ deviation)=0.8241+2\cdot0.0057=0.8355$. Here, $0.8127<0.8133<0.8355$, therefore the value is not unusual, because it is between the minimum and maximum usual value mean.