Half-life prob: How much is left after 35 years?

[mattmurdock]

Ok...one more, then I need to go out for a walk and get some air!

The amount of radioactive element R in grams present t years from now is given by the formula R = 10.9e^(-0.003t). How much of R is present initially? How much is left after 35 years (to the nearest tenth of a gram)?

 

[skeeter]

Re: Half-life equation

The amount of radioactive element R in grams present t years from now is given by the formula R = 10.9e^(-0.003t).

How much of R is present initially? evaluate R for t = 0

How much is left after 35 years (to the nearest tenth of a gram)?
evaluate R for t = 35

 

[mattmurdock]

so presently there would be 10.9

and after 35 years there would be 9.8 left...