The task is to explore the US census population estimates by county for 2015 from the packageusmap(load the data frame fromcountypop.RData). The data frame has3142rows and4variables:fipsis the 5-digit FIPS code corresponding to the county;abbris the 2-letter state abbreviation;countyis the full county name;pop_2015is the 2015 population estimate (in number of people) for the corresponding county. Each row of the data frame represents a different county or a county equivalent. For the sake of simplicity, when we say a county, that also includes a county equivalent and when we say a state, that also includes the District of Columbia. Answer the following questions.

1. How many people live in each of the states?
2. What is the average population of a county in each of the states?