Page 21 - Pharmacy College Admission Test Review Book
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            1.(b)   These  types of  problems can  be  solved  by   Let A be the set of students drinking milk, then
            using the SET THEORY.  There are few terminologies    n(A) = 400
            and  equations  you  should  keep  in  mind  to  solve
            these problems.                                       Let  B  be  the  set  of  students  drinking  coffee,  then
                                                                  n(B) = 300
            A. (U) = It is known as universal set. The universal
            set depends on the context.                           The set of students drinking both milk and coffee is
                                                                  A  B, therefore n(A  B) = 150
            B.  A    B  =  When  every  element  of  set  A  also
            belongs to set B, then set A is said to be the subset   Finally, let the set of students of the school be U,
            of B. For example,                                    therefore n(U) = 800

            A = {1, 2, 3} and B = {0, 1, 2, 3, 4}                 The set of students drinking neither coffee nor milk
                                                                  should be A’  B’ = (A  B)’
            C. When A  B and B  A, then A = B or they are
            called equal sets.                                      n (A  B)’  = n(U) -  n (A  B)
                                                                                 = n(U) - [n(A) + n(B) - n(A  B)
            D. A  B = The set consisting of all elements which                        = 800 - 400 - 300+ 150
            are in A or in B is called the union of A and B, and is               = 250
            denoted by A  B. For example,
                                                                  2. (a) 8. This type of problem can also be solved by
            A = {1, 2, 3} and B = {0, 1, 2, 3, 4}                 using a Venn diagram.
                                                                                                       U
            A  B = {0, 1, 2, 3, 4}
                                                                            M                       B
            E. A  B = The set consisting of all elements which                   y     x     z
            are  common  in  both  A  and  B  is  called  the
            intersection of A and B, and is denoted by A  B.
            For example,
                                                                  Let x = Number of students taking mathematics as
            A = {1, 2, 3} and B = {0, 1, 2, 3, 4}                 well as biology.
                                                                  Let y = Number of students taking mathematics but
            A  B = {1, 2, 3}                                     not biology.

            F. (A’) = The set consisting of all those elements of U   From Venn diagram, we can say:
            which are not in A is called the component of A and
            is denoted by A’. For example,                               x + y = 24
                                                                         x + 16= 24
            U = {1, 2, 3, 4, 5} and A = {1, 2} then,                     x = 8
                                                                  3. (b) This type of problem can be solved by using
            A’ = {3, 4, 5}                                        the Binomial Theorem. Let say a = 2x, b = y and n =
                                                                  5
            G.     De Morgan’s Laws:
                                                                                                    n
                                                                              n
                                                                                       n
                                                                         n
                                                                                  n
                                                                  (a + b) = ( ) a + ( ) a  n−1  + ⋯ ( ) a n−r
            1.     (A  B)’ = A’  B’                                         0        1            r
            2.     (A  B)’ = A’  B’                             (2x + y) =
                                                                          5


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