1. (10 points) The following seven observations are a sample from a normal population: 7,6,11,9,8,5,10 (a) Find the sample mean and sample standard deviation of these data. [20 points] Occasionally, we need to use the union and intersection symbols in a manner analogous to the summation sign . We define i=1nSi=S1S2Sn with an analogous notation for the intersection of several sets. With this notation, the general DeMorgan's laws are written as i=1nSi=i=1nSi and i=1nSi=i=1nSi Prove these identities for all finite values of n. Hint: prove it by induction on " n