Two sprinters leave the starting gate at the same time at the beginning of a straight track. The mass of the first sprinter is m$1=54\mathrm{.}6$kgm$1=54\mathrm{.}6$kg$,$ and the mass of the second sprinter is m$2=67\mathrm{.}8$kgm$2=67\mathrm{.}8$kg$.$

A$.)$ A few seconds later, the first sprinter is ahead of the second by a distance of $5\mathrm{.}92$m$5\mathrm{.}92$m$.$ How far ahead of the second sprinter, in meters, is the center of mass of these two sprinters?

B$.)$ If the speed of the first sprinter is v$1=5\mathrm{.}74$m$/$sv$1=5\mathrm{.}74$m$/$s and the speed of the second sprinter is v$2=2\mathrm{.}59$m$/$sv$2=2\mathrm{.}59$m$/$s$,$ how fast, in meters per second, is the center of mass moving?