The amount, a, in milligrams, of radioactive material remaining in a container can be modeled by the exponential function a(t) = 5(0.5)0.25t, where t is time, in years. based on this model, how many years does it take for half of the original radioactive material to be left remaining?

Zed is making a centerpiece for his dining room table by putting sand in a cube-shaped vase. the vase is 0.25 meters in length, width, and height. he bought 25 kg of sand. assume the density of dry sand is 1,602 kgm3. what is the volume of the sand that zed purchased? the volume of the sand is approximately m3. enter your answer as the number that correctly fills in the blank in the previous sentence. if necessary, round your answer to six decimal places, like so: 42.536475