Let X∼Beta(α,β)X \sim \text{Beta}(\alpha, \beta)X∼Beta(α,β). What is the mean E[X]E[X]E[X]?
αβ\frac{\alpha}{\beta}βα
αα+β\frac{\alpha}{\alpha+\beta}α+βα
α−βα+β\frac{\alpha-\beta}{\alpha+\beta}α+βα−β
1α+β\frac{1}{\alpha+\beta}α+β1