Question 1128753
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Let x be the fraction remaining after one hour.  Then, since the half-life is 7.5 hours,<br>
{{{x^7.5 = 0.5}}}
{{{x = (0.5)^(1/7.5) = 0.9117}}} to 4 decimal places.<br>
The amount remaining decreases by a factor of 0.9117 per hour.  That means the fraction that remains at the end of each hour is<br>
1-0.9117 = 0.0883<br>
I don't know which of those two numbers is your definition of "hourly decay rate".