Depends on how many grams of the sample exist.
Think of half life as the amount of time it takes to split the item in half. With that half life, divide starting the grams by 2 (for the first 60.5 seconds). Because the question is asking for 121 seconds, divide the grams you just divided by 2 again. That should get you your answer.
Hope this helps!
Answer/Explanation:
(altitude to hypotenuse theorem)
Solve for x using this equation
(division property of equality)
(pythagorean theorem)
(substitution)
(pythagorean theorem)
(substitution)
