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Joint Entrance Examination
Mathematics
Probability
Question 281
Question 281 of 417
Medium
MCQ
Mean and variance of a binomial distribution are 4 and 2. Find
P
(
2
successes
)
P(2\text{ successes})
P
(
2
successes
)
.
A
28
/
256
28/256
28/256
B
219
/
256
219/256
219/256
C
128
/
256
128/256
128/256
D
37
/
256
37/256
37/256
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Official solution
p
=
q
=
1
2
,
n
=
8
p=q=\dfrac12,n=8
p
=
q
=
2
1
,
n
=
8
. \[P(X=2) = {}^8C_2\left(\frac12\right)^8 = \frac{28}{256}\]
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