Ateacher has four books—a, b, c, and d—to assign to four students in any order he prefers. set s includes all possible arrangements of the four books. set x includes all possible arrangements when book c is chosen first and d is chosen second. which notation is correct? if book c is chosen first and d is chosen second, in how many ways can the teacher assign the books?

Answer with explanation:

The Number of Books Possessed by the teacher = A, B,C,D

Total possible arrangement of the books,in which order is Important,we will use the concept of Permutation

S={

So, there are 24 elements in set S.

Number of Elements in the set X

              =taking CD as a first element and Either A as third and B as fourth or B as third and A as fourth.

=1+1

=2 ways

Or

Keeping CD as one book, then there are 2 books left,which can be arranged as

=1×2×1

=2 ways

So, if book C is chosen first and D is chosen second, number of ways the teacher can assign the books

     = 2 ways