Chromium 51 is a radioactive substance used in medicine. It has a 1/2 life of 28 days. The equation for its exponential decay model is `y=a(.5)^t/28 If 10 mg is ingested by a patient, how many days before only 8 mg is still emitting radiation?

9 days before only 8 mg is still emitting radiation.

Step-by-step explanation:

The exponential model is:

In which a is y(0), that is, the initial quantity.

10 mg is ingested by a patient

This means that , and thus:

How many days before only 8 mg is still emitting radiation?

This is t for which y(t) = 8. So

9 days before only 8 mg is still emitting radiation.