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KEAM 2019 Math Paper
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© examsnet.com
Question : 56
Total: 121
Number of ways of dividing 7 men and 7 women into 7 couples, with a man and woman each is
7
!
140
70
175
None of these
Validate
Solution:
Number of ways of choosing first couple is
(
7
C
1
)
(
7
C
1
)
=
7
2
Similarly, choosing the second couple
=
(
6
C
1
)
(
6
C
1
)
=
6
2
and so on.
Hence, total number of ways is
7
2
+
6
2
+
5
2
+
4
2
+
3
2
+
2
2
+
1
2
=
49
+
36
+
25
+
16
+
9
+
4
+
1
=
140
© examsnet.com
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