Question

A 15 gram sample of radioactive iodine decays in such a way that the mass remaining after t days is given by m(t)=15e^(-0.087t), where m(t) is measures in grams. After how many days is there only 8 grams remaining?

Answer 1

8
--- = e^(-.087t)
15

8
ln(---) = -.087t
15

ln(8/15)
------- = t
-.087

Answer 2

t = 7.225....

Answer 3

dbl chk and we get: m(t) = 7.999999....

Answer 4

Yayyyy! Thanks again :)

Answer 5

youre welcome :)