Compute user Equivalent Range Error for the following error sources:

Satellite clock error $=2\mathrm{.}5$ m

Ephemeris error $=1\mathrm{.}5$ m

Ionospheric refraction error $=8\mathrm{.}5$ m

Tropospheric refraction error $=1\mathrm{.}5$ m

Receiver noise $=4\mathrm{.}5$ m

Other $($multi$-$path etc.$)=2\mathrm{.}0$ m