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The amount of radioactive substance left at the end of x days can be represented by an exponential function. The initial amount is 100 grams, and the amount left after three days is 72.9 grams. Which function
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Apr 4, 2019
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The amount of radioactive substance left at the end of x days can be represented by an exponential function. The initial amount is 100 grams, and the amount left after three days is 72.9 grams. Which function models the amount of radioactive substance left at the end of x number of days?
a.f(x)=0.85^x
b.f(x)=0.90^x
c.f(x)=100(0.85)^x
d. f(x)=100(0.90)^x
STEPS PLEASE WITH THE ANSWER!! I WAS NEVER TAUGHT THIS!!!!
Mathematics
middle-school
Parnab Sanyal
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Parnab Sanyal
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The general formula for exponential growth/decay is:
so in this case we have:
and correct answer is C or D. Now we have two ways to solve this:
1. Substitute x = 3 days and check wich answer is correct (where we get
72.9).
C)
D)
Correct answer is D)
2. We know that
so we can find value of r.
Our function is:
and again correct answer is D)
Violet
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Apr 9, 2019
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Violet
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