How do we use this?
Well we know the half-life in each case, so what does that mean? It means that the when the time is equal to the half-life only half of the sample is left.
When t = 0
So k is the amount of sample initially, before it started to decay. So when t is equal to the half-life we only have (1/2)k of the substance:
So the decay equation is:
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