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JEE Main Math Class 12 Probability Part 2 Questions
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© examsnet.com
Question : 34
Total: 95
A fair
n
(
n
>
1
)
faces die is rolled repeatedly until a number less than
n
appears. If the mean of the number of tosses required is
n
9
, then
n
is equal to _______.
[12-Apr-2023 shift 1]
Your Answer:
Validate
Solution:
Mean
=
1
⋅
n
−
1
n
+
2
1
n
(
n
−
1
n
)
+
3
(
1
n
)
2
(
n
−
1
n
)
.
.
.
n
9
=
(
n
−
1
n
)
(
1
+
2
(
1
n
)
+
3
(
1
n
)
2
.
.
.
.
.
.
.
)
n
9
=
(
n
−
1
n
)
(
1
−
1
n
)
−
2
=
(
n
−
1
n
)
⋅
n
2
(
n
−
1
)
2
n
9
=
n
n
−
1
⇒
n
=
10
© examsnet.com
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