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Integrals

Question
CBSEENMA12035782

The random variable X can take only the values 0, 1, 2, 3. Given that P(X =0) = P(X = 1) = p and P(X = 2) = P(X = 3) such that Σpixi2 = 2Σpixi, find the value of p.

Solution

It is given that the random variable X can take only the values 0,1,2,3.
Given:
P(X = 0) = P( X =1) =p
P(X =2) =P(X =3)
Let P (X =2) = P(X =3) =q
Now,
P(X =0) + P(X =1) +P(X =2) +P(X =3) =1
⇒ p +p+(q+q) = 1
since Σpixi2 = 2Σpixi,
 rightwards double arrow space 0 space plus straight p left parenthesis 1 right parenthesis squared space plus open parentheses fraction numerator 1 minus 2 straight p over denominator 2 end fraction close parentheses open parentheses left parenthesis 2 squared plus 3 squared close parentheses space equals space 2 open square brackets 0 space plus straight p space plus open parentheses fraction numerator 1 minus 2 straight p over denominator 2 end fraction close parentheses left parenthesis 2 plus 3 right parenthesis close square brackets
rightwards double arrow space straight p space plus 13 over 2 left parenthesis 1 minus 2 straight p right parenthesis space equals 2 space open square brackets straight p space plus 5 over 2 left parenthesis 1 minus 2 straight p right parenthesis close square brackets
rightwards double arrow space straight p space plus 13 over 2 minus 12 straight p space equals space minus 8 straight p plus 5
rightwards double arrow space 4 straight p space equals space 3 over 2
rightwards double arrow space straight p space equals space 3 over 8

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