Question 416076: The half-life of strontium-90 is 28 years. How long will it take a 72 mg sample to decay to a mass of 18 mg?
Your answer is years. Answer by richard1234(5390) (Show Source):
You can put this solution on YOUR website! For this problem, there is no need to use logarithms since it decays from 72 mg to 18 mg (one-fourth of the original amount). Hence, exactly two half-lives are required, so it would take 56 years.
