## A substance decays so that the amount A of the substance left after t years is given by: A = A 0 · (0.75) t , where A 0 is the original am

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## Answers ( No )

Let be the original amount of the substance. After

tyears, the amount leftAis given by:.

For example, after 1 year, the amount is

.

Thus, after one year, only 0.75=3/4 of the original amount is left.

We want to solve for

t, such that is one-third of , so we set the equation:.

Simplifying by , we have:

.

This is an exponential equation, so we can solving it by rewriting it as a logarithm:

.

Answer: 3.8