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A 18 gram sample of a substance that's used to sterilize surgical instruments has a k-value of 0.1226. N = Noe -kt No=invalid mass (at time to =0. N = mass at time t. K=a positive constant that depends on the substance itself and on the units used to measure time. t=time, in days. What is the substances half life, in days rounded to the nearest tenth.

User Priit
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The half-life is defined to be the time it takes for any specified property, in this case, mass, to be half of its original value. Thus, given the equation:
N = No*e^-kt, with N = 9, No = 18, and k = 0.1226, the value of t, in days, can be determined. Solving the equation, the half-life of the substance, or the time it takes for the sample to be 9 grams is 5.7 days.
User Guforu
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