Question

What percent of a substance is left after six hours if a radioactive substance decays at a rate of 3.5% per hour?

Answer 1

Since the amount of the substance becomes 96.5% each hour, the amount `R(t)` of a radioactive substance can be expressed as

`R(t)=R_0(0.965)^t`,

where `R_0` is an initial amount, and `t` is time in hours.

The percentage of the substance after 6 hours can be found by

`{R(6)}/{R_0}cdot100={R_0(0.965)^6}/R_0cdot100 approx 80.75`%

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I hope that this was helpful.