mylab stats 6.4 basic prob and stats
A researcher collects a simple random sample of grade-point averages of statistics students, and she calculates the mean of this sample. Under what conditions can that sample mean be treated as a value from a population having a normal distribution?
If the population of grade point averages has a normal distribution or the sample has more than 30 grade point averages.
Annual incomes are known to have a distribution that is skewed to the right instead of being normally distributed. Assume that we collect a large (n>30) random sample of annual incomes. Can the distribution of incomes in that sample be approximated by a normal distribution because the sample is large? Why or why not?
No; the sample means will be normally distributed, but the sample of incomes will be skewed to the right.
