SOLUTION: Find the decay rate of Arsenic-74 when the half- life is 17.5 days. Round to six decimal places.

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Question 1163965: Find the decay rate of Arsenic-74 when the half- life is 17.5 days. Round to six decimal places.
Found 2 solutions by solver91311, MathTherapy:
Answer by solver91311(24713) About Me  (Show Source):
You can put this solution on YOUR website!


A radioactive substance decays at a rate proportional to the amount remaining.



When half-life is reached,

Hence the name "half-life"

Since the half-life of this particular substance is 17.5 days:



Take the natural log of both sides





You can do any additional arithmetic required.

I sincerely hope you are not surprised that the answer is a negative number.


John

My calculator said it, I believe it, that settles it

Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

Find the decay rate of Arsenic-74 when the half- life is 17.5 days. Round to six decimal places.
If ½ (.5) life is “a” time intervals, then 

The DECAY CONSTANT/RATE, or "k" being < 0 indicates DECAY RATE, since the substance will DECAY and cause its MASS to DECREASE, over time!