Question

after 36.9 years , a sample if tritium contains one-eighth the amount it originally contained, what is the half-life of the isotope?

Answer 1

We can solve this problem using a formula:
\[Amount=Amount _{Original}(1/2)^{(years/half-life)}\]
Plugging in the information given we get:
\[1/8=(1/2)^{(36.9 years/half-life)}\]
Now we know 1/8 is just 1/2 raised to the third power, so (years/half-life) must equal 3.
Knowing that, the half-life must be a third of the 36.9 years, or 12.3 years.