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Question 1
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A = {2, 4, 6, 8}, B = {2, 3, 7, 9} and C = {x: 3 < x < 9} are subsets of the universal-set
U = {2, 3, 4, 5, 6, 7, 8, 9}. Find
(a) A n(B'nC');
(b) (AuB) n(BuC). |
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This question was reportedly attempted by majority of the candidates and their performance
was described as satisfactory. Many of them lost some marks because they failed to use curly
brackets to enclose the elements of the sets. A good number of the candidates were also
reported not to have listed the elements of set C hence, were not able to find its complement
while others did not separate the elements of a set with comas.
Candidates were expected to list the elements of C i.e. C = {4, 5,6, 7, 8}, obtain the compliments
of the sets Band C thus B' = {4,5,6, 8}, C' = {2, 3, 9,}. Using these sets, the following procedures
were to be followed:
(a)(B' nC') = { } Hence An (B' n C') = { }. Some candidates were reported to have
written { 0 } instead of { } or 0.
(b) (A u B) = { 2, 3,4,6, 7, 8, 9 }, (BuC) = {2, 3, 4,5,6, 7, 8, 9 }
Therefore { Au B } n (BuC) = { 2, 3, 4, 6, 7, 8, 9 }.
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