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# The half-life of an isotope is the amount of time required for 50% of

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Math Expert
Joined: 02 Sep 2009
Posts: 51073
The half-life of an isotope is the amount of time required for 50% of  [#permalink]

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29 Jul 2018, 23:52
00:00

Difficulty:

15% (low)

Question Stats:

100% (01:36) correct 0% (00:00) wrong based on 16 sessions

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The half-life of an isotope is the amount of time required for 50% of a sample of the isotope to undergo radioactive decay. The half-life of the carbon-14 isotope is 5,730 years. How many years must pass until a sample that starts out with 16,000 carbon-14 isotopes decays into a sample with only 500 carbon-14 isotopes?

(A) 180 years
(B) 1,146 years
(C) 5,730 years
(D) 28,650 years
(E) 183,360 years

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Re: The half-life of an isotope is the amount of time required for 50% of  [#permalink]

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29 Jul 2018, 23:57
ans: D

given half life is 5730 years So.
500 = 16000(1/2)^n finding n from here gives us n=5; means 5 half life time
5x5730 = 28650

Bunuel wrote:
The half-life of an isotope is the amount of time required for 50% of a sample of the isotope to undergo radioactive decay. The half-life of the carbon-14 isotope is 5,730 years. How many years must pass until a sample that starts out with 16,000 carbon-14 isotopes decays into a sample with only 500 carbon-14 isotopes?

(A) 180 years
(B) 1,146 years
(C) 5,730 years
(D) 28,650 years
(E) 183,360 years

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Re: The half-life of an isotope is the amount of time required for 50% of &nbs [#permalink] 29 Jul 2018, 23:57
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