Amount left = $450 - $171 = $279
Amount left in Percentage = 279/450 x 100 = 62%
Answer: (C) 62%
<h3>
Answer: Choice A</h3>
is not the same as 
The base of the log is p, while the base of the exponential is b. The two don't match. If it said
then it would be a valid statement since the bases are both p.
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Extra info:
Choice B is a valid statement because Ln is a natural log with base 'e'
Choice C is valid as any square root is really something to the 1/2 power
Choice D is valid for similar reasons mentioned earlier
Given that the half-life of the sample is 14.28 days, you are looking for a decay factor

such that

Solving for

yields




Now, after 57 days, you're told that a sample of unknown mass decayed to 55g, which means if

was the starting mass of the sample, then

Solving for

yields
If there was an illustration, I would be happy to assist you.