What is the variance of a probability distribution function of the form: #f(x)=ke^(-2x)#?

Answer 1

The distribution is an exponential distribution. k = 2 and E (x) = 1/2 ,
E ( #x^2# )= 1/2 #=># V (x) = E ( #x^2#) - #{E (x)}^2# - 1/2 - #(1/2) ^2# = 1/2 - 1/4 = 1/4.

The limit of the distribution is (0, #oo# ) To find k, #int_0^B# k #e^- (2x)# dx = k #Gamma# (1)/ 2 = 1 #=># k/2 = 1 #=># k = 2. E (x) = #int_0^Bx
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Answer 2

To find the variance of a probability distribution function of the form ( f(x) = ke^{-2x} ), you first need to determine the value of ( k ) and then apply the formula for variance.

  1. Determining the value of ( k ): Since ( f(x) ) is a probability distribution function, the total area under the curve must equal 1. Thus, you need to find the value of ( k ) that makes the integral of ( f(x) ) over its entire domain equal to 1.

  2. Integral of ( f(x) ) over its domain: The domain of ( f(x) ) depends on the range of ( x ). Assuming ( x ) ranges from ( 0 ) to ( +\infty ), integrate ( f(x) ) from ( 0 ) to ( +\infty ) and set the result equal to 1 to find ( k ):

    [ \int_{0}^{\infty} ke^{-2x} dx = 1 ]

  3. Solve for ( k ): [ k\int_{0}^{\infty} e^{-2x} dx = 1 ] [ k \left( \frac{-1}{2} e^{-2x} \right) \Bigg|_{0}^{\infty} = 1 ] [ k \left( 0 - \frac{-1}{2} \right) = 1 ] [ k \left( \frac{1}{2} \right) = 1 ] [ k = 2 ]

Now that you have found the value of ( k ), which is ( 2 ), you can proceed to find the variance.

  1. Formula for variance: The variance ( \sigma^2 ) of a probability distribution function ( f(x) ) is calculated using the formula:

    [ \sigma^2 = \int_{-\infty}^{\infty} (x - \mu)^2 f(x) dx ]

    Where ( \mu ) is the mean of the distribution.

  2. Calculate the mean ( \mu ): To calculate the mean of ( f(x) ), integrate ( xf(x) ) over its domain:

    [ \mu = \int_{0}^{\infty} x(2e^{-2x}) dx ]

  3. Calculate the variance: Substitute the value of ( k ) into ( f(x) ) and compute the integral to find the mean ( \mu ). Then, use the formula for variance to find ( \sigma^2 ).

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.

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