After 548 hours decreases the activity of a radioactive substance to 1/9 of the initial value. What is the half-life of the substance?

Correct answer:

t1/2 =  172.9 hours

Step-by-step explanation:

(12)548t1/2=19  t1/2=548ln(0.5)ln(1/9)=172.9 hours

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