SOLUTION: suppose that a certain radioactive substance has a half life of 20 years. if there is presently 2500 milligrams of the substance, how much, to the nearest milligram will remain aft
Algebra.Com
Question 434856: suppose that a certain radioactive substance has a half life of 20 years. if there is presently 2500 milligrams of the substance, how much, to the nearest milligram will remain after 40 years? after 50 years?
Found 2 solutions by stanbon, solver91311:
Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
suppose that a certain radioactive substance has a half life of 20 years. if there is presently 2500 milligrams of the substance, how much, to the nearest milligram will remain after 40 years?
----
f(40) = 2500(1/2)^(40/20)
f(40) = 2500(1/4)
f(40) = 625 ml
-------------------------
after 50 years?
f(50) = 2500(1/2)^(50/20)
f(50) = 2500(1/2)^2.5
f(50) = 2500*0.176788 = 441.94 ml
============================
Cheers,
Stan H.
=============
Answer by solver91311(24713) (Show Source): You can put this solution on YOUR website!
\ =\ M_oe^{kt})
Calculate 
when the ratio of )
to 
is 0.5 and 
\ =\ \ln(0.5))
\ =\ \ln(0.5))
}{20}\ \approx\ -0.0347)
Then re-write the function using the calculated value of
\ =\ 2500e^{-0.0347t})
\ =\ 2500e^{-0.0347(40)})
\ =\ 2500e^{-0.0347(50)})
You can do your own calculator work.
John
My calculator said it, I believe it, that settles it
RELATED QUESTIONS
Suppose that a certain radioactive substance has a half-life of 20 years. If there are... (answered by ankor@dixie-net.com)
Suppose that a certain radioactive substance has a half-life of 50 years. If there are... (answered by Fermat)
A radioactive substance has a half-life of 60 years. There is an accident that exposes a... (answered by ankor@dixie-net.com)
Find the half life of a radioactive substance that decays by 20% in 10... (answered by stanbon)
The half-life of a certain radioactive substance is 15 years.
Suppose that at time t =... (answered by ankor@dixie-net.com)
Find the half-life of a radioactive substance that is reduced by 30% in 20... (answered by Madgamer107)
The half-¬life of a radioactive substance is the time it takes for half of the atoms of... (answered by Fombitz)
A certain radioactive substance decays exponentially and has a half-life of 78 years.... (answered by stanbon)
A radioactive substance follows the decay equation dA/dt = kA.
If 20% of the substance... (answered by solver91311)
