A 40 gram sample of a substance thats used for drug research has a k-value of 0.1446. find the substances half-life, in days. round your answer to the nearest tenth.

The applicable decay formula is:

N = No*e^ (-kt)

Where

N = Mass left after time t

No = Original mass

k = constant

t = half life

Using the values given,

N/No = e^ (-0.1446t) = 1/2

ln (1/2) = - 0.1446 t * ln e^1

-0.6931 = - 0.1446 t

t = 0.6331/0.1446 = 4.79 days

Therefore, half-life is 4.8 days.