In practice, the 10% condition is not usually mentioned when estimating means because the samples are generally small, so this problem arises only if the sampling is from a small population. Part 4 For small samples (less than 15), the data must closely follow a normal model. For sample sizes between 15 and 40 or so, the data must be unimodal and reasonably symmetric. When the sample size is larger than 40 or 50, the t methods are safe to use unless the data are extremely skewed. Part 5 Into which range of sample size does this sample fall? Larger than 40 or 50 Less than 15 Between 15 and 40