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rrivera5754
What fraction of a given sample of radioactive nuclide remains after four half lives??
1 half-life: 1/2 left 2: half of that, or 1/4 3: half of that, or 1/8 4: half of that, or 1/16 In general: (1/2)^x, where x is the number of half-lives.
After one half life, half of the substance is gone. After another half life, half of the remaining amount is gone. So you have (1/2)*(1/2) = 1/4 of the amount left over After another half life, half of the remaining amount is gone. So you have (1/2)*(1/2)*(1/2) = 1/8 of the amount left over See where this is going?