Question

At the beginning of an experiment, a scientist has 268 grams of radioactive goo. After 90 minutes, her sample has decayed to 4.1875 grams.
What is the half-life of the goo in minutes?______
Find a formula for G(t), the amount of goo remaining at time t. G(t)=______
How many grams of goo will remain after 65 minutes?_____

Answer 1

HI again

Answer 2

want to do this the easy way?

Answer 3

yass plz

Answer 4

or do you have to do this the
\[A_0e^{-kt}\] way?

Answer 5

either way we can do it

Answer 6

thats basically Pert right?

Answer 7

yeah

Answer 8

then yeah use Pert

Answer 9

\[P=268\]

Answer 10

to find \(r\) as you called it, set
\[4.1875=268e^{90r}\] and solve for \(r\)

Answer 11

ok i know how to do that

Answer 12

you get
\[\frac{4.1875}{268}=e^{90r}\\
\ln(\frac{4.1875}{268}=90r\\
\frac{\ln(\frac{4.1875}{268})}{90})=r\]

Answer 13

i get
\[r=-0.0462098...\]

Answer 14

same

Answer 15

ok so now the formula is G(t)= 268e^-.04521(t)

Answer 16

right and to find the half life set
\[e^{-0.0462t}=\frac{1}{2}\] and solve for \(t\)

Answer 17

ok thnx i got it now