After the minute hand of the wall clock passes for 30 minutes, the distance traveled by the tip of the minute hand is half a circle, 20× 2× π÷2 = 20 π cm = 20 * 3.14 = 62.8cm..

After the minute hand of the wall clock passes 60 minutes, the area swept by the minute hand is a whole circle, 20 cm =0.2 m,

Area =0.2×0.2×π=0.04π (square meter) = 0.2 * 0.2 * 3.14 = 0.1256 square meter.