SOLUTION: Suppose a sample of a radioactive substance weighs 38 mg. One year later, the sample weighs 21.5 mg. What is the half-life of this substance? (Round your answer to two decimal plac

Question 1057609: Suppose a sample of a radioactive substance weighs 38 mg. One year later, the sample weighs 21.5 mg. What is the half-life of this substance? (Round your answer to two decimal places.)
Answer by ankor@dixie-net.com(22740) (Show Source): You can put this solution on YOUR website!
Suppose a sample of a radioactive substance weighs 38 mg.
One year later, the sample weighs 21.5 mg.
What is the half-life of this substance? (Round your answer to two decimal places.)
:
Use the radioactive decay formula: A = Ao*2^(-t/h), where:
A = Amt of remaining after t time
Ao = Initial amt
t = time of decay
h = half-life of the substance
in this problem
A = 21.5
Ao = 38
t = 1 year
h = half life of substance
:

using Natural logs

h =
h = 1.22 yrs is the half life
:
:
Check this with a calc enter: 38*2^(-1/1.22) ~ 21.5

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