Two different radioactive isotopes decay to 10% of their respective original amounts. Isotope A does this is 33 days, while isotope B does this in 43 days. What is the approximate difference in the half-lives of the isotopes?

Question

Two different radioactive isotopes decay to 10% of their respective original amounts. Isotope A does this is 33 days, while isotope B does this in 43 days. What is the approximate difference in the half-lives of the isotopes?
3 days
10 days
13 days
33 days

Steve · Accepted Answer

decaying to 10% takes log0.10/log0.5 = 3.32 half-lives So, A's half-life is 33/3.32 = 9.94 days B's half-life is 43/3.32 = 12.95 days Looks like (a) is the answer

Anonymous · Answer

33 dys

Anonymous · Answer

The two expressions below have the same value when rounded to the nearest hundredth. mc013-1.jpg What is the approximate value of mc013-2.jpg to the nearest hundredth?