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Damm [24]
4 years ago
15

a radioactive substance has a Decay rate of 5% per hour. if 500 hundred grams are present initially, how much of the substance r

emains after 4 hours?
Mathematics
1 answer:
kirza4 [7]4 years ago
3 0
First we have to calculate the half-life
half-life = elapsed time * log (2) / log (bgn amt / end amt)
half-life = 1 hour * 0.30102999566 / log (1 / .95)
half-life = 0.30102999566 / log (<span> <span> <span> 1.0526315789 )
</span> </span> </span>half-life = 0.30102999566 / 0.022276394692
half-life = <span> <span> <span> 13.5134073454 hours
</span> </span> </span>
Ending Amount = Beginning Amount / 2^n
Where "n" = number of half-lives
For 4 hours, "n" equals
4 / 13.5134073454
=<span> <span> <span> 0.2960023255

</span></span></span>Ending Amount = 500 grams / 2^.2960023255
Ending Amount = 500 grams /<span> <span> <span> 1.2277376629
</span> </span> </span>Ending Amount = <span> <span> <span> 407.2531250707 grams

Source:
http://www.1728.org/halflife.htm


</span></span></span>
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