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Question: Answered & Verified by Expert
A random variable X takes the values 1, 2, 3 and 4 such that 2PX=1=3PX=2=PX=3=5PX=4. If σ2 is the variance and μ is the mean of X, then σ2+μ2=
MathematicsProbabilityTS EAMCETTS EAMCET 2018 (04 May Shift 1)
Options:
  • A 42161
  • B 57061
  • C 14961
  • D 34803721
Solution:
1257 Upvotes Verified Answer
The correct answer is: 42161

2PX=1=3PX=2=PX=3=5PX=4

Let PX=3=α.

PX=1

P1+P2+P3+P4=1

α2+α3+α+α5=1

6130α=1

α=3061

Similarly, all values can be found out.

x 1 2 3 4
PX 1561 1061 3061 661

Mean μ=EX=X=14XPXX

=11561+21061+33061+4661

 μ=14961

μ2=5.9666

Variance σ2=4x-μ2Pxx

=x-149612156+x-1496121061+x-1496123061+x-149612661

 σ2=0.935224

μ2+σ2=5.9666+0.935224

=6.901224

μ2+σ2=42161.

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