A thin cylindrical shell of radius R$1=6\mathrm{.}5$cm

is surrounded by a second cylindrical shell of radius R$2=8\mathrm{.}9$cm

$,$ as in the figure Both cylinders are $9\mathrm{.}0$ m

long and the inner one carries a total charge Q$1=0\mathrm{.}92\backslash$mu C

and the outer one Q$2=+1\mathrm{.}60\backslash$mu C

$.$For points far from the ends of the cylinders, determine the magnitude of the electric field at a radial distance r

from the central axis of $7\mathrm{.}4$ cm

$.$