SOLUTION: The function A = A0e^(-0.0099x) models the amount in pounds of a particular radioactive material stored in a concrete vault, where x is the number of years since the material was p

Algebra ->  Customizable Word Problem Solvers  -> Finance -> SOLUTION: The function A = A0e^(-0.0099x) models the amount in pounds of a particular radioactive material stored in a concrete vault, where x is the number of years since the material was p      Log On

Ad: Over 600 Algebra Word Problems at edhelper.com


    

Question 1202994: The function A = A0e^(-0.0099x) models the amount in pounds of a particular radioactive material stored in a concrete vault, where x is the number of years since the material was put into the vault. How many years will it be until 30% of the original amount remains in the vault? Round off to the nearest year.
Answer by josgarithmetic(39616) About Me  (Show Source):
You can put this solution on YOUR website!
A=ae%5E%28-0.0099x%29 to make the text symbols easier to manage

According to question, ....., 0.3=1%2Ae%5E%28-0.0099x%29 and you want to solve for x.


ln%280.3%29=ln%28e%5E%28-0.0099x%29%29
ln%280.3%29=-0.0099x%2Aln%28e%29
ln%280.3%29=-0.0099x%2A1
x=ln%280.3%29%2F%28-0.0099%29---------and you can finish computing this...