SOLUTION: A scientist begins with 250 grams of a radioactive substance. After 250 minutes, the sample has decayed to 32 grams. Rounding to five significant digits, what is the exponential eq

Algebra ->  Rational-functions -> SOLUTION: A scientist begins with 250 grams of a radioactive substance. After 250 minutes, the sample has decayed to 32 grams. Rounding to five significant digits, what is the exponential eq      Log On


   

Question 1138079: A scientist begins with 250 grams of a radioactive substance. After 250 minutes, the sample has decayed to 32 grams. Rounding to five significant digits, what is the exponential equation representing this situation. To the nearest minute, what is the half life of this substance?
Answer by ankor@dixie-net.com(22740) About Me  (Show Source):
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A scientist begins with 250 grams of a radioactive substance.
After 250 minutes, the sample has decayed to 32 grams. Rounding to five significant digits,
what is the exponential equation representing this situation.
:
the radioactive decay formula: A = Ao*2^(-t/h), where
A = amt after t time
Ao = the initial amt
t = time of decay
h = half-life of substance
32 = 250*2^(-250/h)
:
32%2F250 = 2^(-250/h)
:
ln%2832%2F250%29 = ln(2^(-250/h))
:
-2.02557 = -250%2Fh*.6931
-2.0557h = -250 * .6931
h = %28-173.2867%29%2F%28-2.0557%29
h = 84.0 minutes is the half life of this substance?