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By what percent will the bacteria population increase . . .

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by Vincen » Tue Dec 12, 2017 10:28 am
By what percent will the bacteria population increase in 1 hour?

(1) The current population is 300,000 bacteria.

(2) The bacteria population doubles every 15 minutes.

The OA is B.

How can I use statement (2) to get the answer? And why is not sufficient the statement (1)? Experts, may you help me, please?
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Source: — Data Sufficiency |

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by Jay@ManhattanReview » Tue Dec 12, 2017 10:11 pm
Vincen wrote:By what percent will the bacteria population increase in 1 hour?

(1) The current population is 300,000 bacteria.

(2) The bacteria population doubles every 15 minutes.

The OA is B.

How can I use statement (2) to get the answer? And why is not sufficient the statement (1)? Experts, may you help me, please?
(1) The current population is 300,000 bacteria.

We do not have the information about the rate of growth of the bacteria population. Insufficient.

(2) The bacteria population doubles every 15 minutes.

Say initially, the number of bacteria was 100; thus, in 15 minutes, it would be 200; thus, in 30 minutes, it would be 400; thus, in 45 minutes, it would be 800; thus, in 60 minutes, it would be 1600.

The percent increase in the bacteria population in 1-hour = [(1600 - 100)/100]*100% = 1500%. Sufficient.

The correct answer: B

Hope this helps!

-Jay
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