Half life

Determine the half life of bismuth, when bismuth weight from the original weight of 32 g was only 2 grams in 242 minutes.

Correct result:

t =  60.5 min

Solution:

$$\begin{gathered} 32\cdot 0.5^{242\mathrm{/}t}=2 \\ 16=2^{242\mathrm{/}t} \\ \ln 16=242\mathrm{/}t\cdot \ln 2 \\ \ln 16\mathrm{/}\ln 2=242\mathrm{/}t \\ t=60.5\text{ min} \end{gathered}$$

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