Question

The amount of radioactive substance y that remains after t years is given by the equation y=ae^kt, where a is the initial amount present and k is the decay constant for the radioactive substance. If a = 100, y=50, and k=-0.035, find t

so far i have...
50=100e^-0.035(t), then what?

Answer 1

uhhhhhh?

Answer 2

no idea?

Answer 3

You set it up correctly, now just have to solve. Start by dividing both sides by 100.

Answer 4

\[.5=e^-0.035(t)\]?

Answer 5

Yes. Now you need to get the t by itself. Think inverse of the e function...

Answer 6

uhmm..

Answer 7

i'm sorry i really have no idea. I get everything in the classroom and then when i get home and doing homework i get so lost.

Answer 8

Ok ln is the inverse of e. So if we take the ln of both sides we get ln(.5)=-.035t sorry for a later response...

Answer 9

thats okay.