A percolation tube is used to determine the percolation rate of a soil sample in mL/cm2/minute. To conduct the test, a certain volume of water is poured through the soil sample, and the time it takes for the water to pass through the sample is measured. Calculate the percolation rate using the following data. (Remember, area= pi•r^2). b. A percolation tube has a radius of 4.5 cm; 50 mm of water is poured onto the surface of the soil and it takes 10 seconds for the water to disappear from the surface of the soil.