What is a z-score? Z-score is literally just measuring how many standard deviations away from the mean. Just like that. So we literally just have to calculate how many standard deviations each of these guys are from the mean, and that's their z-scores. So let me do number or part a. So we have 65. So first we can just figure out how far is 65 from the mean, let me just draw one chart here that we could use the entire time.