Select the correct answer from each drop-down menu. a scientist is observing a sample of a radioactive substance. the table below shows the amount of the radioactive substance remaining, in milligrams, with respect to time, in hours, since the scientist began observing the sample. time (hours) 1 2 3 4 5 amount remaining (milligrams) 288 144 72 36 18 the independent variable in the relationship is the(time or amount remaining)and should be placed on the(x or y ). the dependent variable in the relationship is the(time or amount remaining)and should be placed on the(x or y ).