Answer:
The fraction of original isotope remaining after 12 weeks is 1/8 (0.125)
Explanation:
The half life of the radio-isotope = 4 weeks =[tex]t_{\frac{1}{2}}[/tex]
After n half lives, the fraction of original isotope remaining = [tex]\frac{1}{2^{n}}[/tex]
In 12 weeks, the number of half lives = 12/4 = 3 half lives
The fraction of original isotope remaining = [tex]\frac{1}{2^{3}}=\frac{1}{8}[/tex]
Hence, after 12 weeks, fraction of original isotope remaining is 1/8 (0.125)
