Question 1156506
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An {{{highlight(cross(isotype))}}} <U>isotope</U> of Sodium, Na-24, has a half life of 10h. 
If a sample contains 400 units of Na-24, the exponential function to model this is y=400(1/2)^x.

What does the variable y represent in this situation?
What does the variable x represent in this situation? 

Im confused and don't know how to figure this out. 
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<pre>
The variable "y" represents the current amount of the isotope NA-24 in the sample after x half-life periods.


The variable "x" represents the number of half-life periods after the beginning of the decay process.


For example, x = 2 means "2 half-life periods", i.e. 2*10 = 20 hours.
</pre>

Answered and solved.


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Notice that the formula in your post &nbsp;IS &nbsp;NOT &nbsp;traditional and &nbsp;DIFFERS &nbsp;from the traditional decay function/formula.


The traditional decay formula for this isotope would be   &nbsp;&nbsp;y = {{{400*(1/2)^(t/10)}}}, &nbsp;where &nbsp;t &nbsp;is the time in hours.