A) \[90\]
B) \[15\]
C) \[9\]
D) 45
Correct Answer: D
Solution :
If elements are not repeated then number of elements in \[{{A}_{1}}\cup {{A}_{2}}\cup {{A}_{3}}\cup ......\cup {{A}_{30}}\] is \[30\times 5.\] but each element is used 10 time. \[\therefore \] \[S=\frac{30\times 5}{10}=15\] ?..(i) Similarly, if elements in \[{{B}_{1}},\,{{B}_{2}}.....{{B}_{n}}\] are not repeated, then total number of elements is 3n but each elements is repeated 9 times. \[S=\frac{3n}{9}\] \[\Rightarrow \] \[15=\frac{3n}{9};\] [from Eq. (i)] \[\therefore \] \[n=45\]You need to login to perform this action.
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