Which of the following are true: 1. As the size of a sample increases, the mean of the distribution of sample mean also increases. 2. As the size of a sample increases, the standard deviation of the...

Which of the following are true:

1. As the size of a sample increases, the mean of the distribution of sample mean also increases.

2. As the size of a sample increases, the standard deviation of the distribution of sample mean decreases.

3.  A sampling distribution is normal only when the population is normal.

4. If the size of the sample is at least 30, then you can use z-scores to determine the probability that a sample mean falls in a given interval of the sampling distribution.