Exercise 7. Standard error of the estimate

In practice, we don't know $p$, so we construct an estimate of the theoretical prediction based by plugging in $\bar{X}$ for $p$. Calculate the standard error of the estimate: $$\hat{\mbox{SE}}(\bar{X})$$

Simulate a poll X using the sample function.
When using the sample function, create a vector using c() that contains all possible polling options where '1' indicates a Democratic voter and '0' indicates a Republican voter.
When using the sample function, use replace = TRUE within the sample function to indicate that sampling from the vector should occur with replacement.
When using the sample function, use prob = within the sample function to indicate the probabilities of selecting either element (0 or 1) within the vector of possibilities.
Use the mean function to calculate the average of the simulated poll, X_bar.
Calculate the standard error of the X_bar using the sqrt function and print the result.