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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