aliffeyip4erebell aliffeyip4erebell

21-11-2016
Physics

contestada

the half life of a certain substance is 25 years. How long will it take for a sample of this substance to decay to 90% of its original amount ...?

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andriansp andriansp

23-11-2016

10% = 1/2 ^n
*where n is number of half lives to reach 10%

n = ln10/ln2

and multiply by 25 gives 83.05 years to 2dp

Hope this helps

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