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6.Permutation and Combination
normal
Let $n(A) = 3, \,n(B) = 3$ (where $n(S)$ denotes number of elements in set $S$), then number of subsets of $(A \times B)$ having odd number of elements, is-
A
$64$
B
$128$
C
$256$
D
$512$
Solution
$\mathrm{n}(\mathrm{A} \times \mathrm{B})=9$
${\,^9}{{\rm{C}}_1} + {\,^9}{{\rm{C}}_3} + \ldots \ldots + {\,^9}{{\rm{C}}_9} = {2^8} = 256$
Standard 11
Mathematics