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cell population doubles at constant intervals

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cell population doubles at constant intervals

by netigen » Sun Jun 01, 2008 1:14 am
A scientist is studying bacteria whose cell population doubles at constant intervals, at which times each cell in the population divides simultaneously. Four hours from now, immediately after the population doubles, the scientist will destroy the entire sample. How many cells will the population contain when the bacteria is destroyed?

(1) Since the population divided two hours ago, the population has quadrupled, increasing by 3,750 cells.

(2) The population will double to 40,000 cells with one hour remaining until the scientist destroys the sample.
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by jasonc » Sun Jun 01, 2008 4:19 am
answer is D
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by s_raizada » Sun Jun 01, 2008 5:33 am
I think answer is A

1. we can find out the total cells at currect point in time

Let x be cells two hours ago
so 4x - x = 3750
x = 1250
So total cells now are 5000. This also tells us the frequency means cells are doubling every hour.

so total cells at the end of four hours period will be 80 k

2. no information about the frequency of doubling for example if cells double every half an hour then total cells will be 160k but if cells double every hour then total cells will be 80k
Not suff
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by jasonc » Sun Jun 01, 2008 12:59 pm
yep my bad.
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by netigen » Sun Jun 01, 2008 1:17 pm
OA is C
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by jasonc » Sun Jun 01, 2008 2:06 pm
oops again :)

stem1 doesn't give us frequency either, since the frequency could be 1 hr or 45 min, or xxx hrs. So we need stem2 combined with stem1 to help with determining frequency.
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by simplyjat » Sun Jun 01, 2008 8:38 pm
This is one of the questions from MGMAT whose explanation is hard to buy. OA states that first statement does not give the frequency! I might be bad in English, but if "Since the population divided two hours ago" is not specifying the frequency as 1 hour, WTF else does the statement specifies.

One can be sure of not finding this kind of question in GMAT.
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by jasonc » Sun Jun 01, 2008 9:32 pm
simplyjat wrote:This is one of the questions from MGMAT whose explanation is hard to buy. OA states that first statement does not give the frequency! I might be bad in English, but if "Since the population divided two hours ago" is not specifying the frequency as 1 hour, WTF else does the statement specifies.

One can be sure of not finding this kind of question in GMAT.
all stem1 says is that we're currently between the second time it doubled and the third time since it first divided 2 hours ago. We can't find a specific frequency from this. I don't think there are any issues with the wording of the stem statement, but it is a tricky question.
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by jimmyjamesdonkey » Mon Jun 30, 2008 4:58 pm
How does this question differ from this one: https://www.beatthegmat.com/can-anyone-e ... 13274.html
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