A certain population of bacteria doubles every 10 minutes.

[BTGModeratorVI]

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

Answer: C
Source: Official Guide

[Brent@GMATPrepNow]

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

Answer: C
Source: Official Guide

Let's list some populations and look for a pattern

Initial population: 10⁴
10 minutes later: (10⁴)(2)
20 minutes later: (10⁴)(2)(2)
30 minutes later: (10⁴)(2)(2)(2)
40 minutes later: (10⁴)(2)(2)(2)(2)
50 minutes later: (10⁴)(2)(2)(2)(2)(2)
60 minutes later: (10⁴)(2)(2)(2)(2)(2)(2) = (10⁴)(2⁶)

Answer: C

Cheers,
Brent

[Scott@TargetTestPrep]

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

Answer: 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