This exercise uses the radioactive decay model. The half-life of strontium-90 is 28 years. How long will it take a 40-mg sample to decay to a mass of 27.2 mg? (Round your answer to the nearest whole number.) yr

Half-Life The half-life of radium-226 is approximately 1620 years. a. How much of sample weighing 4 g will remain after 100 hours? b. How much time is necessary for a sample weighing 4 g to decay to 0.1 g?

The half-life of radioactive actinium ( 227AC ) is 21.77 years. What percent of a present amount of radioactive actinium will remain after 19 years?

Suppose that the initial mass of radioactive substance is m0 and the half-life of the substance is h. Let m(t) be the mass remaining at time t. a What is meant by the half-life h? b Write a formula for m(t) in terms of the half-life h. c Write a formula for the relative decay rate r in terms of the half-life h. d Write a formula for m(t) in terms of the relative decay rate r.