Now use dplyr to add a confidence interval as two columns, call them lower and upper, to the object poll. Then use select to show the pollster, enddate, x_hat,lower, upper variables. Hint: define...

Now use dplyr to add a confidence interval as two columns, call them lower and upper, to the object poll. Then use select to show the pollster, enddate, x_hat,lower, upper variables. Hint: define temporary columns x_hat and se_hat.

The final tally for the popular vote was Clinton 48.2% and Trump 46.1%. Add a column, call it hit, to the previous table stating if the confidence interval included the true proportion p = 0.482 or not.