Question 1149578
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The general formula is


    M = M0/(2^(t/28)),


Where M0 is the initial mass;  M is the current (remaining) mass, and "t" is time in years.



So, the answers (and the calculation work) are


(a)  M = 10/(2^(1/28)) = 9.755 grams;


(b)  M = 10/(2^(10/28)) = 7.807 grams.
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