1. The problem statement, all variables and given/known data Suppose that an investigator believes that virtually all values in the population are between 38 and 70. The appropriate sample size for estimating the true population mean within 2 units with 95% confidence level is approximately how much? 2. Relevant equations Variance of the sampling distribution of size n = Variance of the population distribution / n 3. The attempt at a solution I think I'm solving 1.96(SD of the sampling distribution of size n)=2 But I don't think there's any information given on the population variance so I don't know what to do.