The Thiessen weights of 4 raingauges A, B, C, and D covering a river basin are 0.15, 0.25, 0.30, and 0.30, respectively. If the average depth of rainfall for the basin is 5 cm, and the rainfalls recorded at B, C, and D are 5 cm, 4 cm, and 5 cm respectively, what will be the rainfall at A?