The mass of a radioactive element at time t is given by
where
is the mass at time zero, while 
is the half-life of the element.
In our problem,
, t=121.0 s and 
, so we can find the initial mass :
where
In our problem,
One way to describe a wave crest is the amount of ___________ applied over an area.
2 answers:
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Explanation:
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