Question 1118001
z=(x-mean)/sd
For a. (11.6-11.8)/0.2 is a z<-1 a probability 0.1587
For b it is z between -1 and -2. This probability is 0.1359
For c it is z greater than 2  which has probability of 0.0228.  This may be considered an unusual event depending upon what criteria/probability one chooses to call unusual.