SOLUTION: The radioactive isotope you discovered at 8 am weighed 75 mg. At 3 pm it measured only 0.009 grams. Rounded to the nearest whole minute, what is its half life?

Question 857775: The radioactive isotope you discovered at 8 am weighed 75 mg. At 3 pm it measured only 0.009 grams. Rounded to the nearest whole minute, what is its half life?
Answer by josgarithmetic(39617) (Show Source): You can put this solution on YOUR website!
, I is initial amount, A is final amount after time t.

FIND k

USE k TO FIND HALF-LIFE
Decay equation is .
Let A=1/2 and let I=1.
Solve for t.
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