Correct Answer - C
Consider the following events :
A=X speaks truth, B=Y speaks truth.
Then,
P
(
A
)
=
60
100
=
3
5
and
P
(
B
)
=
50
100
=
1
2
P
Required probability
=
P
(
(
A
∪
¯¯¯
B
)
∪
(
¯¯¯
A
∩
B
)
)
=
P
(
A
∩
¯¯¯
B
)
+
P
(
¯¯¯
A
∩
B
)
P
=
3
5
×
1
2
+
2
5
×
1
2
=
1
2
=