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# The population of a bacteria culture doubles every 2 minutes. Approxim

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Joined: 14 Jul 2010
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The population of a bacteria culture doubles every 2 minutes. Approxim [#permalink]

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17 Feb 2011, 03:26
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35% (medium)

Question Stats:

68% (01:09) correct 32% (01:09) wrong based on 97 sessions

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The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the population to grow from 1,000 to 500,000 bacteria

A. 10
B. 12
C. 14
D. 16
E. 18

OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/the-populatio ... 67378.html
[Reveal] Spoiler: OA

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Re: The population of a bacteria culture doubles every 2 minutes. Approxim [#permalink]

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17 Feb 2011, 03:39
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KUDOS
The question basically asks how many minutes it takes for a population to increase by factor 500 (500,000 / 1,000 = 500).

Now you know that every two minutes the population doubles, i.e. is multiplied by 2. So the equation becomes:

2^x >= 500, where x represents the number of times the population doubles. A lot of people remember that 2^10 = 1,024. Hence, 2^9 = 512, i.e. the population has to double 9 times.

Since it takes the population 2 minutes to double once it takes 9*2 minutes = 18 minutes to double nine times.

Thus, solution E = 18 is correct.
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Re: The population of a bacteria culture doubles every 2 minutes. Approxim [#permalink]

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27 Jan 2018, 22:29
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Re: The population of a bacteria culture doubles every 2 minutes. Approxim [#permalink]

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27 Jan 2018, 23:33
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The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the population to grow from 1,000 to 500,000 bacteria?

(A) 10
(B) 12
(C) 14
(D) 16
(E) 18

$$1000 * 2^t = 500,000$$ --> $$2^t = 500$$ --> since $$2^9 = 512$$, then $$t\approx{9}$$. Thus, approximately 9 two-minute intervals are needed, whcih is 18 minutes.

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OPEN DISCUSSION OF THIS QUESTION IS HERE: http://gmatclub.com/forum/the-populatio ... 67378.html
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Re: The population of a bacteria culture doubles every 2 minutes. Approxim   [#permalink] 27 Jan 2018, 23:33
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