Irne has four books that she wants to put on a library shelf. Three of these books

Irène has four books that she wants to put on a library shelf. Three of these books form a 3-volume set of a dictionary, so that they are marked as Volumes I, II, and III, respectively.

(i) Find an appropriate sample space for all possible ways she can put the books on the shelf.

(ii) Identify the elements of this sample space that each of the following three events contains:

B1: the three volumes of the dictionary are put next to one another;

B2: the three volumes of the dictionary are put in the right order (but not necessarily in adjacent places), so that Volume I is placed to the left of Volume II, which in turn is placed to the left of Volume III;

B3: the three volumes of the dictionary are placed next to one another and in the right order.