Question
The half-life of a radioactive substance is 5 hours. How
much of the substance remains after 15 hours?Solution
Each half-life reduces the substance to half. In 15 hours, there are three half-lives (15 ÷ 5). So the remaining amount is: (1/2)³ = 1/8 Hence, 1/8 of the substance remains after 15 hours.
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