7choose a number b at random from the interval [0, 1] with uniform density. find the probability that (a) 1/3 < b < 2/3. (b) |b − 1/2| ≤ 1/4. (c) b < 1/4 or 1 − b < 1/4. (d) 3b2 < b

ending amount = beginning amount / (2^n)

where "n" = number of half-lives (or elapsed time / half-life)

ending amount = 50 mg / (2 ^10 / 5.3)

ending amount = 50 mg / (2 ^ 1.8867924528)

ending amount = 50 m / 3.6981210597

ending amount = 13.5203794557 mg

or about 13.5 mg remain

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the correct answers are 1, 2, 4, and 5! i just got it right!