There may be more than one correct statement, Check all that are true

1. In interval estimation of the population mean, the fundamental difference between the t and z procedures is that we us et for small sample sizes and z for large sample sizes
2. On average , the sample mean equals the population mean
3. All else being equal , a 99% confidence interval for mu will be wider than the corresponding 95% interval.
4. If the sample size is small , the sampling distribution of the sample mean cannot be normal