Water is running into a bathtub at a constant rate. after 2 minutes, the tub is filled with 2.5 gallons of water. write two equations for this proportional relationship. use w for the amount of water (gallons) and t for the time ( minutes). in each case, what does the constant of proportionality tell you about the situation?

The weight of a radioactive isotope was 96 grams at the start of an experiment. after one hour, the weight of the isotope was half of its initial weight. after two hours, the weight of the isotope was half of its weight the previous hour. if this pattern continues, which of the following graphs represents the weight of the radioactive isotope over time? a. graph w b. graph x c. graph y d. graph z