Question 1130837
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The original amount was 200mg; after 4 hours the amount was cut in half, to 100mg.  Since the model is to be exponential, we know that the amount remaining in the body will get cut in half every 4 hours.<br>
Then if t is the number of hours that have passed, t/4 is the number of 4-hour periods that have passed.  So the amount remaining in the body after t hours has been cut in half (multiplied by .5) t/4 times.<br>
With the original dose of 200mg, the number of mg in the body after t hours is<br>
{{{200*(.5)^(t/4)}}}