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The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the popula

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by BTGModeratorVI » Sat Aug 08, 2020 7:05 am
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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

Answer: E
Source: Official guide
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Re: The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the po

by Brent@GMATPrepNow » Tue Aug 11, 2020 6:02 am
BTGModeratorVI wrote: ↑
Sat Aug 08, 2020 7:05 am
 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

Answer: E
Source: Official guide
When we scan the answer choices (ALWAYS scan the answer choices BEFORE deciding on the approach you'll take), we see that the number of population "doublings" will be between 5 and 9.
Given these relatively small values, we might solve this question by creating a growth table

MINUTES ELAPSED | POPULATION
0 | 1,000
2 | 2,000
4 | 4,000
6 | 8,000
8 | 16,000
10 | 32,000
12 | 64,000
14 | 128,000
16 | 256,000
18 | 512,000 DONE!!

Answer: E

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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