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

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

Sol: We need to find the population of the bacteria 1 hour later. Let Initial Population be x =10^4
After 10 mins: 2x
20 mins: 4x
30 mins: 8x
40 mins: 16x
50 mins: 32x
60 mins: 64 x--------> 2^6*x -----> 2^6*10^4. Ans C
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Re: A certain population of bacteria doubles every 10 minutes. If the [#permalink]
An hour has 6 10-min intervals. If the population of bacteria doubles(2x) every 10 mins, then in 1 hour it will have multiplied by 2^6 times.

So, after 1 hour it will be (2^6)(10^4).

Ans is (C)
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Re: A certain population of bacteria doubles every 10 minutes. If the [#permalink]
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Let us solve this using the GP extension
Here R i.e the common multiple =2
after 60 minutes => 7th term => 2^6*64
Smash that C
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Re: A certain population of bacteria doubles every 10 minutes. If the [#permalink]
Hello Moderators,

Do you think the answers choices need to be made math Friendly? On a quick look, Option B and Option E "look" the same (Which of course is not the case). This ambiguity can be removed if answer choices are made math friendly.

Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 22
Category: Arithmetic Operations on rational numbers
Page: 64
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

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Re: A certain population of bacteria doubles every 10 minutes. If the [#permalink]
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Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 22
Category: Arithmetic Operations on rational numbers
Page: 64
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

=====

(10^4)
After 10 mins, 2*(10^4)
After 20 mins, 2*(2*(10^4))
After 10 mins,
Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 22
Category: Arithmetic Operations on rational numbers
Page: 64
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

=====

(10^4)
After 10 mins, 2*(10^4)
After 20 mins, 2*2*(10^4)
After 30 mins, 2*2*2*(10^4))
After 40 mins, 2*2*2*2*(10^4)
After 50 mins, 2*2*2*2*2*(10^4)
After 60 mins, 2*2*2*2*2*2*(10^4)

2^6 * (10^4)

Hence, Answer is (2^6)(10^4) = C

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Re: A certain population of bacteria doubles every 10 minutes. If the [#permalink]
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Bunuel wrote:
The Official Guide For GMAT® Quantitative Review, 2ND Edition

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

Problem Solving
Question: 22
Category: Arithmetic Operations on rational numbers
Page: 64
Difficulty: 600

GMAT Club is introducing a new project: The Official Guide For GMAT® Quantitative Review, 2ND Edition - Quantitative Questions Project

Each week we'll be posting several questions from The Official Guide For GMAT® Quantitative Review, 2ND Edition and then after couple of days we'll provide Official Answer (OA) to them along with a slution.

We'll be glad if you participate in development of this project:
2. Please vote for the best solutions by pressing Kudos button;
3. Please vote for the questions themselves by pressing Kudos button;
4. Please share your views on difficulty level of the questions, so that we have most precise evaluation.

Thank you!

Every 10 minutes population of bacteria = 2 times
Every 60 minutes population of bacteria becomes = 2*2*2*2*2*2= 2^6 times

Since initially population of bacteria = 10^4

Population of bacteria after 1 hour ( 60 minutes) =( 2^6) * (10^4)

IMO C

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