A well pump test was made in a surface layer of sand 10m thick overlying impervious clay. Before the test the water table was at 1.5m depth. After steady state had been reached in the tests, sounding wells at radii of 20m and 40m showed drops in level of 1.85m and 1.18m respectively and the rate of flow was 5.6 m3/min. Determine the value of k in m/sec.