A radioactive substance decays by $12 \%$ every year. Which of the following is the formula for the quantity, $Q$, of a 10 gram sample remaining after $t$ years?
A) $Q=10(0.88)^{t}$
B) $Q=10(1.12)^{t}$
C) $Q=10(-1.12)^{t}$
D) $Q=10(-0.88)^{t}$

Question

Quizplus · Accepted Answer

The formula for exponential decay is $Q = Q_0(1 - r)^t$, where $Q_0$ is the initial quantity, $r$ is the decay rate, and $t$ is time. Here, $Q_0 = 10$ grams, $r = 0.12$, so $Q = 10(0.88)^t$.

A Radioactive Substance Decays By 12%12 \%12% Every Year QQQ , of a 10 Gram Sample Remaining After

A Radioactive Substance Decays By $12 \%$ Every Year $Q$ , of a 10 Gram Sample Remaining After