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The weight of a radioactive sample is given by the function
where is the time, in years, and is the weight of the sample, in ounces.
What is the weight of the sample when ?
Suggested Answer: C
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The function is:
This is an exponential decay function because the base is between 0 and 1:
That means the sample's weight decreases over time.
We need to find the weight when:
Substitute into the function:
First calculate the exponent:
Now multiply by :
Rounded to two decimal places:
So the weight of the radioactive sample after 3 years is approximately:
20 comments · newest first
NA
Nadine
7 days ago
Same here!
TW
Twanna
12 days ago
I just hope I get it right!
TO
Tommy
17 days ago
I agree with B. It matches my calculations.
JO
Jolene
23 days ago
A is too high for a radioactive sample.
AS
Ashley
28 days ago
I prefer A. It seems more reasonable.
KI
Kirk
1 month ago
Because it fits the decay model.
EV
Eva
1 month ago
Why B?
KI
Kirk
1 month ago
I believe the answer is B.
RY
Ryan
2 months ago
I feel unsure about the calculations.
TH
Thad
2 months ago
I think it's about decay.
ME
Melinda
2 months ago
This question is tricky.
WY
Wynell
2 months ago
Radioactive decay is exponential, just FYI!
PA
Paulene
2 months ago
Are we sure those options are correct? Seems off.
GO
Golda
2 months ago
Wait, how do we even know the initial weight?
MA
Marci
3 months ago
I think it's option B! Sounds right to me.
VI
Viola
3 months ago
The weight decreases over time due to radioactive decay.
XO
Xochitl
3 months ago
I’m confused about the units. Are we supposed to convert anything before calculating the weight?
HE
Heidy
3 months ago
I feel like we did a practice question on radioactive decay last week. I think the answer was related to the half-life concept.
VI
Vincenza
3 months ago
I’m not entirely sure how to plug in the time value correctly. Did we practice something similar in class?
DE
Desire
4 months ago
I think I remember that radioactive decay functions usually involve an exponential decay formula. I hope I can apply that here.