Let X be an exponential random variable with parameter λ=2 . Find the values of the following. Use 'e' for the base of the natural logarithm (e.g., enter e^(-3) for e−3 ).
a) E[(3X+1)2]=
b) P(1≤X≤2)=

Respuesta :

Answer:

a

[tex]E[(3X+1)^2]= 8.5  [/tex]

b

[tex]P(1 <  X < 2)=0.1170 [/tex]

Step-by-step explanation:

From the question we are told that

   The parameter of  X  is  [tex]\lambda  =  2[/tex]

Generally the expected value of  X is  

    [tex]E(X) =  \frac{1}{\lambda }[/tex]

     [tex]E(X) =  \frac{1}{2}[/tex]

=>  [tex]E(X) =  0.50 [/tex]

Generally we have that

     [tex]E(X^2) =  E(X)^2 + E(X)^2[/tex]

=>  [tex]E(X^2) =  [\frac{1}{2}] ^2 + [\frac{1}{2} ]^2[/tex]

=>  [tex]E(X^2) =  0.5 [/tex]

Generally

    [tex]E[(3X+1)^2]= E(9x^2 + 1 + 6x)[/tex]

=>  [tex]E[(3X+1)^2]= 9E[X^2] + 1 + 6 E[X])[/tex]

=>    [tex]E[(3X+1)^2]= 9* 0.5  + 1 + 6 * 0.5 [/tex]

=>   [tex]E[(3X+1)^2]= 8.5  [/tex]

Generally  

   [tex]P(1 <  X < 2)=  P(X < 2) - P(X < 1)[/tex]

Here  [tex]P(X <  2 ) =  e^{- 2 * \lambda }[/tex]

=>      [tex]P(X <  2 ) =   e^{- 2 * 2 }[/tex]

=>       [tex]P(X <  2 ) =   e^{- 4}[/tex]

and  

    [tex]P(X <  1 ) =   e^{- 1 * \lambda }[/tex]

    [tex]P(X <  1 ) =   e^{- 1 * 2 }[/tex]

    [tex]P(X <  1 ) =   e^{-2 }[/tex]

So

   [tex]P(1 <  X < 2)= e^{-2 } -  e^{- 4} [/tex]

  [tex]P(1 <  X < 2)=0.1170 [/tex]