Question

Flourine-20 has a half-life of 11 seconds. This can be modeled by the function

f(x)=a(12) t where t is the number of half-lives and a is the original amount in grams. If there is a 40 gram sample, how many grams will be left after 44 seconds?
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Answer 1

The function given is incorrect
f(t) = a x 2^-t. Where a is the original quantity and t is the number of half-lives
f(4) = 40 x 2^-4 = 2.5 grams

Start with 40g
After 11 seconds you have 40/2 = 20g
After 22 seconds you have 10g
After 33 seconds you have 5g
After 44 seconds you have 2.5g