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A certain galaxy is known to comprise approximately 4 x 10^11 stars. O

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A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 06 Oct 2014, 14:45
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A certain galaxy is known to comprise approximately 4 x 10^11 stars. Of every 50 million of these stars, one is larger in mass than our sun. Approximately how many stars in this galaxy are larger than the sun?

A. 800
B. 1,250
C. 8,000
D. 12,000
E. 80,000
[Reveal] Spoiler: OA

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A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 06 Oct 2014, 14:58
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4*10^11
50 mln = 5*10^7

we divide 10^11 by 10^7 and we get (10^4)*4 = 40,000 and divide by 5. the result is 8,000 (c)
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A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post Updated on: 07 Oct 2014, 01:18
Answer = C

\(\frac{4 * 10^{11}}{50 * 10^6} = 8 * 10^3 = 8000\)
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Originally posted by PareshGmat on 06 Oct 2014, 19:02.
Last edited by PareshGmat on 07 Oct 2014, 01:18, edited 1 time in total.
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Re: A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 06 Oct 2014, 23:10
PareshGmat wrote:
Answer = C

\(\frac{4 * 10^{11}}{50 * 10^5} = 8 * 10^3 = 8000\)
.

A million has 6 zeros. I guess there is a typo! :-D
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Re: A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 12 Nov 2014, 11:46
I have a different approach to these problems. I wrote out 4x10^11 and 50 million right under it so that I could quickly divide.

400,000,000,000
50,000,000

4x10^11 is 400 billion. 400 billion is 400,000 millions. 400,000/50 = 8,000

Answer C!
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Re: A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 15 Feb 2015, 15:06
A similar solution:

\(4*10^4 = 5*10^7x\) (x because we are told "of every 50 mil of these stars). So,

\(x =\) \(\frac{4*10^4}{5*10^7}\)

\(x =\) \(\frac{4}{5}\) * \(10^4\)

\(x =\) \(\frac{40000}{5}\)

\(x = 8000\)
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Re: A certain galaxy is known to comprise approximately 4 x 10^11 stars. O [#permalink]

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New post 07 Feb 2018, 12:20
Hi All,

This question is really just about simplifying a fraction. You can either write the given numbers in Scientific Notation OR you can write out all of the zeroes and cancel them out.

Based on the information in the prompt, we're asked to simplify the following fraction:

(4 x 10^11)/(50,000,000)

We can rewrite the denominator as: (5 x 10^7)...

(4 x 10^11)/(5 x 10^7)

Now we can simplify the Scientific Notation....

(4 x 10^4) /(5) =

40,000/5 = 8,000

Final Answer:
[Reveal] Spoiler:
C


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Re: A certain galaxy is known to comprise approximately 4 x 10^11 stars. O   [#permalink] 07 Feb 2018, 12:20
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