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# A certain population of bacteria doubles every 10 minutes. If the numb

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Math Expert
Joined: 02 Sep 2009
Posts: 52971
A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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03 Dec 2014, 07:23
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Difficulty:

5% (low)

Question Stats:

82% (01:10) correct 18% (01:31) wrong based on 167 sessions

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Tough and Tricky questions: Exponents.

A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^5, then what was the number in the population 1 hour later?

A) 2(10^5)
B) 6(10^5)
C) (2^6)(10^5)
D) (10^6)(10^5)
E) (10^5)^6

Kudos for a correct solution.

Source: Chili Hot GMAT

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Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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03 Dec 2014, 08:09
2
x bacteria would become 2x in 10 mins, which would become 4x in the next 10 (total 20 mins)...
So in 60 mins x becomes 2^6 times into x

Therefore Answer is C, (2^6)(10^5)
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Joined: 21 Jul 2014
Posts: 124
Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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03 Dec 2014, 08:10
1
Bunuel wrote:

Tough and Tricky questions: Exponents.

A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^5, then what was the number in the population 1 hour later?

A) 2(10^5)
B) 6(10^5)
C) (2^6)(10^5)
D) (10^6)(10^5)
E) (10^5)^6

Kudos for a correct solution.

Source: Chili Hot GMAT

I did this problem by noticing a pattern. Since the population doubles every 10 minutes, basically all we are doing is doubling our coefficient in front of 10^5. It starts out at (1)10^5 and after 10 minutes it is (2)10^5 and at 20 its (4)10^5. I noticed every 10 minutes we are increasing our power of 2.

An hour is 60 minutes, so the bacteria will double 6 times. This means that our coefficient will end up being 2^6. Looking at the answer choices, choice (C), (2^6)(10^5) is correct.
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Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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03 Dec 2014, 19:08
4
Answer = C) (2^6)(10^5)

Initial value $$= 10^5$$

Interval = 10 Minutes

Intervals in 60 Minutes $$= \frac{60}{10} = 6$$

In one hour, value $$= 2^6 * 10^5$$
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Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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03 Dec 2014, 20:38
2
Present population: 10^5
60 mins will have 6 intervals of 10 mins --> so the population will get doubled 6 times in 1hr --> 2*2*2*2*2*2*10^5 -->2^6*10^5

Illustration:
Present - 10^5
after 10 mins - 2*10^5
after 20 mins - 2(2*10^5) = 2^2*10^5
after 30 mins - 2*(2(2*10^5)) = 2^3*10^5
.
.
.
after 60 mins - 2^6*10^5

Ans. C) (2^6)(10^5)
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Posts: 52971
Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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04 Dec 2014, 06:17
Bunuel wrote:

Tough and Tricky questions: Exponents.

A certain population of bacteria doubles every 10 minutes. If the number of bacteria in the population initially was 10^5, then what was the number in the population 1 hour later?

A) 2(10^5)
B) 6(10^5)
C) (2^6)(10^5)
D) (10^6)(10^5)
E) (10^5)^6

Kudos for a correct solution.

Source: Chili Hot GMAT

The correct answer is C.
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Posts: 52971
Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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04 Dec 2014, 06:23
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Re: A certain population of bacteria doubles every 10 minutes. If the numb  [#permalink]

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29 Sep 2018, 17:20
1
Seems like a rip off of this OG10 question by whoever "created" this question :-/

https://gmatclub.com/forum/a-certain-po ... 65536.html
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Re: A certain population of bacteria doubles every 10 minutes. If the numb   [#permalink] 29 Sep 2018, 17:20
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# A certain population of bacteria doubles every 10 minutes. If the numb

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