A bike tire advertises that it is designed to be used for at least 4,000 km of riding. If the diameter of the tire is 0.7 m, how many rotations of the tire against the ground is that guaranteed, to the nearest thousand? There are 1,000 meters in a kilometer.

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