(5p² - 3) - (2p² - 3p³)
(5p² - 2p²) - 3 + 9p³
3p² - 3 + 9p³
Randomly assigned group. the art class isn't random and only consists of a select type of people--it is not a representative sample; maybe more left handed people enjoy art than do right handed people! therefore, even though the randomly assigned group is smaller, it is the better estimate.
