# 7th grade

posted by
**Kipper**
.

Radon-22 has a half life of 4 days. If you begin with 32 grams of radon, how many grams will be left after 20 days?

posted by
**Kipper**
.

Radon-22 has a half life of 4 days. If you begin with 32 grams of radon, how many grams will be left after 20 days?