Given data
*The half lifetime of potassium-hild is T = 5.63 years
*The given amount is N = 200.0 g
*The given time is t = 36 year
The expression for the radioactivity decay is given as
[tex]N=N_0(\frac{1}{2})^{\frac{t}{T}}[/tex]Substitute the values in the above expression as
[tex]\begin{gathered} N=200(\frac{1}{2})^{\frac{36}{5.63}} \\ N_{}=2.63\text{ g} \end{gathered}[/tex]