The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the only additional descriptive statistic reported for thIs data is the standard deviation which is 1.2 hours a.Calculate the (minimum) percentage of individuals who sleep between 3.9 and 9.9 hours b.Calculate (maximum) percentage of individuals whose sleeping hours are more than 1.8 hours above or below the mean (namely. the , proportion of all individuals who either sleep too much or little")