A) 36
B) 33
C) 20
D) 6
Correct Answer: A
Solution :
[a] Let R = \[\{x:x\in N,x\] is a multiple of 3 and \[x\le 100\}\] and S = \[\{x:x\in N,x\] is a multiple of 5 and \[x\le 100\}\] \[\therefore R=\{3,6,9,12,15...99\}\] And \[S=\{5,10,15,...,95,100\}\] Now, \[(R\times S)\cap (S\times R)=(R\cap S)\times (S\cap R)\] \[=(15,30,45,60,75,90)\times (15,30,45,60,75,90)\] \[\therefore \]Number of elements in \[(R\times S)\cap (S\times R)\] \[=6\times 6=36\]You need to login to perform this action.
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