A sample originally contains 24 grams of a radioactive isotope. After 18 days, 18.8 grams of the isotope remains in the sample.
What is the half-life of the isotope?
yf = yo e-kt
18 .8 = 24e(-k 18)
k = .0135665
1/2 of 24 is 12 grams remaining at t = 1/2 life
12= 24e-(.051287 t)
Solve for t = 51.09 days