A fully penetrating well in a 33-m-thick confined aquifer pumps at a constant rate of 2,000 rn3/day for a long time. In two observation wells located 20 JU and 160 m from the well, the difference in. hydraulic head is 2.0 m. If the undisturbed head is 250 m and the head in the furthest observation well is 249 m, calculate the radius of influence of the well.