The half-life of a radioactive substance is
25
25 years. If you start with some amount of this substance, what fraction will remain in
75
75 years? What fraction will remain in
125
125 years?
The fraction that will remain in in
75
75 years is the following.

nothing
(Simplify your answer.)
The fraction that will remain in in
125
125 years is the following.

nothing
(Simplify your answer.)