Calcium-47, which decays by beta emission, has a half-life of 4.5days: how many milligrams of an initial 24mg of calcium-47 remain after 36days?

how many days are required for 9.60mg of calcium-47 to decay to 1.2mg?

Paleontologists have found plant fossils deep within the layers of the north polar region. these leaf fossils have been labeled as to the rock layers they were found in, with the lower numbers being layers close to the earth's surface and higher numbers representing deeper layers. according to the numbers of these four leaf fossils, what might you infer?