Thread: Can someone help me with this expoential decay problem?

"Suppose a radioactive substance decays at a rate of 3.5% per hour. What percent of the substnce is left after 6 hours?"
Can you please list what I would have to do to solve this problem?

Hey EJdive43.

Does it decay continuously or only in hourly intervals?

Hello, EJdive43!

A radioactive substance decays at a rate of 3.5% per hour.
What percent of the substance is left after 6 hours?

First, set up the function.

The substance loses 3.5% every hour.
That is, 96.5% of the substance remains.

We have: . . where

When , we have: .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . .

Therefore: .