What fraction (in decimal notation) of the pesticide remains in the environment after 15 days?

Question

The half-life of a pesticide determines its persistence in the environment. A common pesticide degrades in a first-order process with a half-life of 2 days. What fraction (in decimal notation) of the pesticide remains in the environment after 15 days? Enter to 4 decimal places.

Answer 1

See my answer to your question on DDT.

FR = 0.5ⁿ

FR = ?

n = 15/2 = 7.5 half lives

0.005524 remains