Correct Answer - C
Total number of elementary events
=
6
3
=
.
Total number of ways of getting 9 as the sum
= Coefficient of
x
9
in
(
x
1
+
x
2
+
x
3
+
x
4
+
x
5
+
x
6
)
3
x
= Coefficient of
x
6
in
(
1
+
x
+
x
2
+
x
3
+
x
4
+
x
5
)
3
x
= Coefficient of
x
6
in
(
1
=
x
6
1
−
x
)
3
x
= Coefficient of
x
6
in
(
1
−
x
)
−
3
=
.
6
+
3
−
1
C
3
−
1
=
.
8
C
2
=
28
x
∴
∴
Favourable number of elementary events =28.
So, required probability
=
28
216
=
7
54
=
