Which of these is true for the normal distributions?

[answerhappygod]

a) \(μ_y = a_1 μ_1 + a_2 μ_2 +⋯+ a_n μ_n\)
b) \(μ_y = a_1 μ_1^2 + a_2 μ_2^2 +⋯+ a_n μ_n^2\)
c) \(μ_y^2 = a_1^2 μ_1^2 + a_2^2 μ_2^2 +⋯+ a_n^2 μ_n^2\)
d) \(σ_y^2 = a_1^2 σ_1^2 + a_2^2 σ_2^2 +⋯+ a_n^2 σ_n^2\)