Matching a uniform and an exponential

Let X∼Uniform(0,λ)X \sim \text{Uniform}(0, \lambda) and Y∼Exponential(λ)Y \sim \text{Exponential}(\lambda) (rate λ\lambda), with λ>0\lambda > 0. For what value of λ\lambda do XX and YY have the same variance? Give λ\lambda to three decimal places.

Show hints (2)+
  1. Recall Var⁡(Uniform(0,λ))=λ2/12\operatorname{Var}(\text{Uniform}(0,\lambda)) = \lambda^2/12 and, for the rate convention, Var⁡(Exponential(λ))=1/λ2\operatorname{Var}(\text{Exponential}(\lambda)) = 1/\lambda^2.
  2. Setting them equal gives λ4=12\lambda^4 = 12. Take the positive fourth root.

Answer

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1.861 (± 0.01)

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