Fraction remaining or decayed after a number of half-lives

1. A.
   1:15
2. B.
   1:4
3. C.
   4:5
4. D.
   5:4

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1. A.
   8.5%
2. B.
   12.5%
3. C.
   25%
4. D.
   87.5%

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1. A.
   $\frac{1}{16}$
2. B.
   $\frac{1}{4}$
3. C.
   $\frac{1}{8}$
4. D.
   $\frac{1}{24}$

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1. A.
   $45$ hour
2. B.
   $60$ hour
3. C.
   $75$ hour
4. D.
   $90$ hour

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1. A.
   $9 : 7$
2. B.
   $7 : 3$
3. C.
   $3 : 7$
4. D.
   $3 : 1$

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1. A.
   $25\%$
2. B.
   $50\%$
3. C.
   $75\%$
4. D.
   $90\%$

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1. A.
   $\dfrac{1}{16}$
2. B.
   $\dfrac{1}{32}$
3. C.
   $\dfrac{1}{256}$
4. D.
   $\dfrac{1}{128}$

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1. A.
   $\left(\dfrac{1}{27}\right)$ of the original value
2. B.
   $\left(\dfrac{1}{9}\right)$ of the original value
3. C.
   $\left(\dfrac{1}{18}\right)$ of the original value
4. D.
   $\left(\dfrac{1}{3}\right)$ of the original value

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1. A.
   $0.25 \times 10^{10}$
2. B.
   $1.5 \times 10^{10}$
3. C.
   $1.75 \times 10^{10}$
4. D.
   $2 \times 10^{10}$

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