A certain population of bacteria doubles every 10 minutes.

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swerve: Legendary Member; Posts: 2539; Joined: Sun Oct 29, 2017 2:04 pmFollowed by: 6 members

by swerve » Thu Dec 19, 2019 5:18 am

A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^4, what was the number in the population 1 hour later?

A. 2(10^4)
B. 6(10^4)
C. (2^6)(10^4)
D. (10^6)(10^4)
E. (10^4)^6

The OA is C

Source: Official Guide

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Source: Beat The GMAT — Data Sufficiency | Thu Dec 19, 2019 5:18 am

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Thu Dec 19, 2019 6:16 am

swerve wrote:A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^4, what was the number in the population 1 hour later?

A. 2(10^4)
B. 6(10^4)
C. (2^6)(10^4)
D. (10^6)(10^4)
E. (10^4)^6

The OA is C

Source: Official Guide

Let's list some populations and look for a pattern

Initial population: 10â�´
10 minutes later: (10â�´)(2)
20 minutes later: (10â�´)(2)(2)
30 minutes later: (10â�´)(2)(2)(2)
40 minutes later: (10â�´)(2)(2)(2)(2)
50 minutes later: (10â�´)(2)(2)(2)(2)(2)
60 minutes later: (10â�´)(2)(2)(2)(2)(2)(2) = (10â�´)(2â�¶)

Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8144; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

by Scott@TargetTestPrep » Thu Dec 26, 2019 8:19 pm

swerve wrote:A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^4, what was the number in the population 1 hour later?

A. 2(10^4)
B. 6(10^4)
C. (2^6)(10^4)
D. (10^6)(10^4)
E. (10^4)^6

The OA is C

Source: Official Guide

Since one hour has 6 ten-minute intervals, after one hour the population is 10^4 x 2^6.

Answer: C

Scott Woodbury-Stewart
Founder and CEO
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