Question

Iron-59 has a half-life of 45.1 days. How old is an iron nail if the Fe-59 content is 25% that of a new sample of iron?

Answer 1

25=100 e^(-.693 t/45.1)
Ln(25)=ln(100) -.693 t/45.1 ln(25)-ln(100)=-.693 t/45.1
ln(25/100)=-.693t/45.1 t= - 45.1/.693 ( ln .25) t=90.2 days I put and it was wrong

Answer 2

@TacianaCampbelll Let me try...

Ln(25)=ln(100) -.693 t/45.1
ln(25)-ln(100)=-.693 t/45.1
ln(25/100)=-.693t/45.1

t= - 45.1/.693 ( ln .25)

t=90.2 days. \(\checkmark\) Is Correct !!

Answer 3

How this happen!!!!