Given a random sample of size n from a population with mean μ and variance, σ2, the sample mean has the following expected value and variance:
1
\( \mathrm{E}(\bar{x})=\mu \) \( \operatorname{Var}(\bar{x})=\sigma^2 / \mathrm{n} \)
2
\( \mathrm{E}(\bar{x})=\mathrm{n} \mu \) \( \operatorname{Var}(\bar{x})=\mathrm{n} \sigma^2 \)
3
\( \mathrm{E}(\bar{x})=\mu \) \( \operatorname{Var}(\bar{x})=\sigma^2 \)
4
\( \mathrm{E}(\bar{x})=\mu \) \( \operatorname{Var}(\bar{x})=\mathrm{n} / \sigma^2 \)