I have another question...

According to the IQR rule, an observation is labelled as a potential outlier if it is more than

1.5xIQR above the upper quartile, or 1.5xIQR below the lower quartile, where IQR denotes the

inter-quartile range. Show that, for a sample from a normally distributed population the IQR rule

identifies any observation that is more than 2.7 standard deviations from the mean as an outlier.