The mass of the body is found by simply weighing a person on a scale. The volume of the body is most easily and accurately determined by completely immersing a person in water and calculating the volume of water from the weight of water that is displaced (via underwater weighing).
Mailman Salary Statistics as of 2015. Average annual salary for a Mailman is $36600 based on statistics in the U.S. as of 2015. The highest salary recorded was $76765. The lowest salary reported was $15604. These figures will vary on a state to state basis as these are averages across all 50 states.
If you're weighing the advantages and disadvantages of being a rural postal carrier, salary probably comes into play. The 2012 median pay of the nation's approximate 500,000 postal carriers was $53,100 per year, or $25.53 per hour, according to the U.S. Bureau of Labor Statistics.