James wants to find the percentage of teenagers who have used e-cigarettes in the past. 30 teens were asked if they have smoked an e-cigarette in the past year. 22 confirmed that they had. Which statement is true? James is estimating... O a mean and will use the t-table because the population standard deviation is unknown O a proportion and will use the Z-table O a mean and will use the t-table because the population standard deviation is known a mean and will use the Z-table because the population standard deviation is unknown O a proportion and will use the t-table O a mean and will use the Z-table because the population standard deviation is known Question Help: Message instructor Submit