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Skewness of a shifted Laplace distribution

Question

A continuous random variable has density λ2e−λ∣x−μ∣\tfrac{\lambda}{2}e^{-\lambda|x-\mu|} on the real line, with constants λ>0\lambda>0 and μ>0\mu>0. Assuming its first three moments are finite, find its skewness E[((X−μX)/σX)3]\mathbb{E}\left[\left((X-\mu_X)/\sigma_X\right)^3\right].

Short answer

00. The density is symmetric about μ\mu, so μX=μ\mu_X=\mu and the third central moment is the integral of an odd function, u3e−λ∣u∣u^3e^{-\lambda|u|}, over the whole line, which vanishes.

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