Jerrail Amazon is deciding where to locate a necessary regional distribution center to serve population centers in Nashville, Seattle, New Orleans, and Lubbock. The cities' locations on an $x-y$ grid and the anticipated annual volume of goods, in tons, are displayed in the following table. Use the center$-$of$-$gravity method to find the best location of the distribution center. $($The number pairs for each answer are in order of $x,y.)$

$\backslash$table$[[$City$,x-$coordinate,$y-$coordinate,Volume$],[$New Orleans,$9,0,100,000],[$Seattle$,1,6,400,000],[$Nashville$,10,2,700,000],[$Lubbock$,6,2,200,000]]$

a$.7\mathrm{.}5,2\mathrm{.}0$

b$.6\mathrm{.}8,3\mathrm{.}0$

c$.5\mathrm{.}7,2\mathrm{.}4$

d$.6\mathrm{.}5,2\mathrm{.}5$