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Joint Entrance Examination
Mathematics
Probability
Question 285
Question 285 of 417
Medium
MCQ
Mean and variance of a binomial
X
X
X
are 4 and 2. Find
P
(
X
=
1
)
P(X=1)
P
(
X
=
1
)
.
A
1
/
4
1/4
1/4
B
1
/
32
1/32
1/32
C
1
/
16
1/16
1/16
D
1
/
8
1/8
1/8
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Official solution
p
=
q
=
1
2
,
n
=
8
p=q=\dfrac12,n=8
p
=
q
=
2
1
,
n
=
8
. \[P(X=1) = {}^8C_1\left(\frac12\right)^8 = \frac{8}{256}=\frac{1}{32}\]
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