1. The problem statement, all variables and given/known data The isotope 239Pu has a half-life of 24,100 years. After 10,000 years, a sample of the isotope is reduced 1.6 grams. What was the intial size of the same (in grams)? How large was the sample after the first 1,000 years. Round your answer to four decimal places. 2. Relevant equations A=Aoert 3. The attempt at a solution Intially, for the value of A, I subbed in "Ao-1.6" and then did the following: Ao-1.6=Aoer10,000 Divided each side by Ao, and then take the Ln of both sides. That's where I get stuck. My calculator is indicating that it's not possible to take the Ln of a negative number.