The function A A e00090 models the amount in pounds of a pa

The function A = A e^-0.0090 models the amount in pounds of a particular radioactive stored in a concrete vault, where x is the number of years since the material was put into vault. If 400 pounds of the material are initially put into the vault, how many pounds will be left after 40 years? a. 350 pounds b. 269 pounds c. 1.14 pounds d. 119 pounds

Solution

A = Ao*e^(-0.0099*x)
putting values:
A = 400*e^(-0.0099*40)
A = 400*e^(-0.396)
A = 400*0.673
= 269 pound
Answer: b