$3\mathrm{.}5.$ A contined aquifer extends $3\mathrm{.}5$ km between the West River and the East River. The water surface elevations of the IVers are $230$ m and $228\mathrm{.}5$ m respectively. The radius of influence of a fully penetrating pumping well located halfway between the ivers is $90$ m $.$ The well has a diameter of $0\mathrm{.}5$ m and pumps at a rate of $75\frac{L}{\text{m}\text{i}\text{n}}.$ The eleyation of the upper confining unit is $227$ m and the aquifer is $25$ m thick. The transmissivity of the aquiter is $80\frac{m^2}{d}.$ Determine the steady state head $20$ m to the east of the well.