Question 1148203
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The general formula for the remaining amount is


    M(t) = M(0)*2^(-t/1690),


where  M(0)  is the initial mass in grams;  t is the time in years.


Substitute your data to get


    M(in 210 years) = 30*2^(-210/1690) = 30*2^(-0.12426) = 27.524 grams (approximately)    <U>ANSWER</U>
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Solved.