SOLUTION: 6.8.9 Question Help The​ half-life of radium is 1690 years. If 40 grams are present​ now, how much will be present in 440 ​years? _______ grams ​(

Algebra ->  Customizable Word Problem Solvers  -> Misc -> SOLUTION: 6.8.9 Question Help The​ half-life of radium is 1690 years. If 40 grams are present​ now, how much will be present in 440 ​years? _______ grams ​(      Log On

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Question 1089273: 6.8.9 Question Help
The​ half-life of radium is 1690 years. If 40 grams are present​ now, how much will be present in 440 ​years?
_______ grams
​(Do not round until the final answer. Then round to the nearest thousandth as​ needed.)
Found 2 solutions by josgarithmetic, ikleyn:
Answer by josgarithmetic(39613) About Me  (Show Source):
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y=p%2Ae%5E%28-kt%29
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If half life 1690 years, then k=ln%282%29%2F1690=0.0004101;
y=p%2Ae%5E%28-0.0004101t%29.

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Let p=40, t=440, find y.

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y=33 grams

Answer by ikleyn(52754) About Me  (Show Source):
You can put this solution on YOUR website!
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The correct answer is 33 grams.