A random survey of 400 out of 20000 likely voters found that the ballot measure was favored by 220 people. Based on these results, predict the number of people hwo will vote in favor of the ballot measure.
The ratio of the number people in favor of the ballot measure to the total number of people is assumed to be the same both for the sample of 400 voters and for the whole population of 20000 likely voters.
This results in the following proportion: 220/400 = x / 20000, where x is the number of people who will vote in favor of the ballot measure. Cross-multiplication yields x = 220 * 20000 / 400 = 11000.