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erik [133]
3 years ago
14

Cobalt-60 has a half-life of about 5 years. How many grams of 300 g sample well remain after 20 years?

Mathematics
2 answers:
Crank3 years ago
5 0
20/5 = 4 half lives

so 

<span>300 * (1/2)^4
</span>= 300 * 0.0625
=18.75 grams



serious [3.7K]3 years ago
3 0

Answer:

<em>After 20 years </em><em>18.75 gm</em><em> of sample will remain.</em>

Step-by-step explanation:

This is the case of an exponential decay of Cobalt-60. The function for exponential decay is,

y(t)=a(1-r)^t

where,

y(t) = amount left after time t  

a = initial amount = 300 g

r = rate of decay = 0.5 (as the sample is getting halved each time)

t = number of periods = \dfrac{20}{5}=4 (as we have to convert the period in terms of half lives)

Putting the values,

y(t)=300(1-0.5)^4=300(0.5)^{4}=\dfrac{75}{4}=18.75\ gm


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