The decay of 742 mg of an isotope is described by the function A(t)= 742e-0.03t, where t is time in years. Find the amount left after 84 years. Round your answer to the nearest mg.

Question

whpalmer4 · Answer

$$A(t) = 742e^{-0.03t}$$All you need to do is plug in $t=84$ and evaluate it...

whpalmer4 · Answer

Do you have a calculator?

anonymous · Answer

what about e?

whpalmer4 · Answer

$e \approx 2.71828182284590452354$ is the base of the natural logarithm.  

Yes, $-0.03$ is part of the exponent, it's the decay constant.

whpalmer4 · Answer

Does your calculator have an button labeled e^x, perhaps?

anonymous · Answer

Yes I think i got it from here thank you :)

whpalmer4 · Answer

Okay, I'll check your answer if you want.

anonymous · Answer

59.7?

whpalmer4 · Answer

Here's a graph of that function from t=1 to t=100

whpalmer4 · Answer

Here's the point where you read the problem statement again while checking your work: "round your answer to the nearest mg"

Yes, I got 59.701 as the answer before rounding.

anonymous · Answer

ok thanks for the help!

whpalmer4 · Answer

You're welcome!

anonymous · Answer

how do you do the work????

whpalmer4 · Answer

The problem gives you the formula, and the numbers to plug into the formula.  Do so, and round the answer as instructed.