For a random sample of households in the US, we record annual household income, whether the location is east or west of the Mississippi River, and number of children. We are interested in determining...

For a random sample of households in the US, we record annual household income, whether the location is east or west of the Mississippi River, and number of children. We are interested in determining whether there is a difference in average household income between those east of the Mississippi and those west of the Mississippi.

a) Define the relevant parameter(s) and state the null and alternative hypotheses.

b)
What statistic(s) from the sample would we use to estimate the difference?