Suppose that a city is made up of three counties Washington

Suppose that a city is made up of three counties: Washington County, Adams County, and Jefferson County. In the population of gas stations in the city, 25 percent are in Washington County, 30 percent are in Adams County, and 45 percent are in Jefferson County. In a population of gas stations in Washington County, the mean price of regular gas is $2.25 with a standard deviation of $0.24. In a population of gas stations in Adams County, the mean price of regular gas is $2.31 with a standard deviation of $0.31. In a population of gas stations in Jefferson County, the mean price of regular gas is $2.35 with a standard deviation of $0.34. Find the mean and standard deviation for the price of regular gas for the population of gas stations in the city overall.

Solution