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5. We can show that linear combinations of normally distributed random variables are nor- mally distributed using MGFs. Let Yi ~N(μ, σ2), where i 1, are independent. Consider each of the linear combinations X below, and determine their mean and variance . . . , n. Assume that the (b) X-Ση.1 aiYi, with the ai constants (c) x-ri Zi, where Zi-Yi-2 (d) X = n Σ-i Zi, where Zi (e) Now let Yi ~N(μ, σ. ). Determine the mean and variance of X-:-1 wiY, with Yi

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