Lisa B.

asked • 11/06/16

Exponential Growth/Decay PLEASE HELP/Problem in the description.

In many cases, removing dangerous chemicals from waste sites can be modeled using exponential decay. This is a key reason why such cleanups can be dramatically expensive. Suppose for a certain site there are initially 20 parts per million of a dangerous contaminant and that our cleaning process removes 5% of the remaining contaminant each day.

How much contaminant (in parts per million) is removed during the first five days? Round your answer to two decimal places.
 
_____________ ppm

2 Answers By Expert Tutors

By:

Michael J. answered • 11/06/16

Tutor
5 (5)

Applying SImple Math to Everyday Life Activities

Andrew M.

That will tell you how much is left.
To find out how much was taken you have
to then take   P0-P
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11/06/16

Lisa B.

Thank You !!!!! This problem was driving me insane. lol
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11/06/16

Andrew M. answered • 11/06/16

Tutor
New to Wyzant

Mathematics - Algebra a Specialty / F.I.T. Grad - B.S. w/Honors

Michael J.

The unit is already in parts per million.  So no conversion is needed in the calculation.
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11/06/16

Andrew M.

I did not perform any conversion.
The question asks how many parts per
million were removed, not how many were left.
To find the final answer one must subtract the
ppm left (P) from the nitial amount (p0).
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11/06/16

Andrew M.

My apologies... it is 20 ppm... Not sure how I read
20,000,000 ppm ... Your answer is correct, but still
incomplete.  You still have to take P0-P to find the
final answer.
 
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11/06/16

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