SOLUTION: i can not figure out what to plug in for the rate in the following word problem... The radioactive element iodine-131 has a half-life of 8 days and is often used to help patients

Question 109464: i can not figure out what to plug in for the rate in the following word problem...
The radioactive element iodine-131 has a half-life of 8 days and is often used to help patients with thyroid problems. If a certain thyroid procedure requires .5g and is scheduled to take place in 3 days, what is the minimum amount that must be on hand now? I am using the equation A=A_oe^rt
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
The radioactive element iodine-131 has a half-life of 8 days and is often used to help patients with thyroid problems. If a certain thyroid procedure requires .5g and is scheduled to take place in 3 days, what is the minimum amount that must be on hand now?
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A(t) = Ao(1/2)^(t/8)
0.5 = Ao(1/2)^(3/8)
0.5 = Ao [0.7711...]
Ao = 0.6484... g
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Cheers,
Stan H.
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