# Math

posted by
**Kate**
.

How long will it take for a 1 g sample of Polonium 210 to lose all but 1/28 of its radioactivity if the half-life is 140 d?

posted by
**Kate**
.

How long will it take for a 1 g sample of Polonium 210 to lose all but 1/28 of its radioactivity if the half-life is 140 d?