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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, 04:26
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45% (medium)

Question Stats:

65% (01:04) correct 35% (01:16) wrong based on 119 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

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

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17 Feb 2011, 04:39
1
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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Joined: 02 Sep 2009
Posts: 48037
Re: The population of a bacteria culture doubles every 2 minutes. Approxim  [#permalink]

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28 Jan 2018, 00:33
1
1
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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Re: The population of a bacteria culture doubles every 2 minutes. Approxim &nbs [#permalink] 28 Jan 2018, 00:33
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