The half-life of plutonium-241 is approximately 13 years. a. How much of a sample weighing 3 g will remain after 70 years? b. How much time is necessary for a sample weighing 3 g to decay to 0.1 g? nts a. After 70 years, g will remain. (Do not round until the final answer. Then round to four decimal places as needed.) ess