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# In a certain population, 40 percent of all people have biological char

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Joined: 02 Sep 2009
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In a certain population, 40 percent of all people have biological char  [#permalink]

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01 Feb 2018, 23:27
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35% (medium)

Question Stats:

70% (00:52) correct 30% (00:35) wrong based on 25 sessions

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In a certain population, 40 percent of all people have biological characteristic X; the others do not. If 8000 people have characteristic X, how many people do not have X?

(A) 3200
(B) 4800
(C) 12000
(D) 16000
(E) 20000

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Re: In a certain population, 40 percent of all people have biological char  [#permalink]

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02 Feb 2018, 00:15
Bunuel wrote:
In a certain population, 40 percent of all people have biological characteristic X; the others do not. If 8000 people have characteristic X, how many people do not have X?

(A) 3200
(B) 4800
(C) 12000
(D) 16000
(E) 20000

Looking at the highlighted part we can infer that

40% of total population = 8000

Let total population = x

i.e. (40/100)*x = 8000

i.e. x = 20000

remaining people = 20000-8000 = 12000

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In a certain population, 40 percent of all people have biological char  [#permalink]

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02 Feb 2018, 07:30
Bunuel wrote:
In a certain population, 40 percent of all people have biological characteristic X; the others do not. If 8000 people have characteristic X, how many people do not have X?

(A) 3200
(B) 4800
(C) 12000
(D) 16000
(E) 20000

Having Biological Characteristic is 40%
Not Having Biological Characteristic is 60%

Thus, people not having character X is $$\frac{8000}{40}*60 = 12000$$

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In a certain population, 40 percent of all people have biological char  [#permalink]

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02 Feb 2018, 10:49
Bunuel wrote:
In a certain population, 40 percent of all people have biological characteristic X; the others do not. If 8000 people have characteristic X, how many people do not have X?

(A) 3200
(B) 4800
(C) 12000
(D) 16000
(E) 20000

8,000 people with X constitute (equal) 40 percent of the whole population, P
The rest, 60 percent of P, do not have X

P = ?
$$8,000 = .40P$$
$$P =\frac{8.000}{\frac{4}{10}}=8,000*\frac{10}{4}=20,000$$

60 percent of total population P do not have X
People with no X: $$(.60*20,000)= 12,000$$

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Re: In a certain population, 40 percent of all people have biological char  [#permalink]

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05 Feb 2018, 10:27
Bunuel wrote:
In a certain population, 40 percent of all people have biological characteristic X; the others do not. If 8000 people have characteristic X, how many people do not have X?

(A) 3200
(B) 4800
(C) 12000
(D) 16000
(E) 20000

We can let n = the total number of people in the population and create the equation:

0.4n = 8000

n = 20,000

So 20,000 x 0.6 = 12,000 do not have the characteristic X.

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Re: In a certain population, 40 percent of all people have biological char &nbs [#permalink] 05 Feb 2018, 10:27
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