Exercise

# Exercise 4. Polling - standard error of X-bar

What is the standard error of the sample average, \(\bar{X}\)?

The variable \(N\) represents the sample size and \(p\) is the proportion of Democrats in the population.

Instructions

### Possible answers

$$\mbox{SE}(\bar{X}) = \sqrt{Np (1-p)}$$

$$\mbox{SE}(\bar{X}) = \sqrt{p (1-p) / N}$$

$$\mbox{SE}(\bar{X}) = \sqrt{p (1-p)}$$

$$\mbox{SE}(\bar{X}) = \sqrt{N}$$