The formula for half-life is [tex]A=A_02^{ \frac{-t}{T_{1/2}} [/tex]. [tex]A_0 = 960[/tex], [tex]t_{1/2} = 60[/tex], [tex]t=180[/tex]. [tex]A = 120[/tex]. This answer is reasonable because it smaller than the starting value, and it accounts for having it three times basically.
120 grams
