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GMAT prep decimal

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Source: — Data Sufficiency |
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by amitansu » Sun May 04, 2008 9:16 pm
E is the answer.
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by jain0069 » Mon May 05, 2008 12:53 am
I think the answer is D.

Here's how..

1. The tenth digit of 100Z is 2.

Therefore:

100Z = .2XXXXXX (the X's dont matter)
Hence,
Z = .2XXXX / 100
Or
Z = .002XXXXX

So the hundredth digit of Z is 0. Sufficient.

2. The unit digit of 1000Z is 2. This is basically saying the same thing as statement 1. However, just taking this alone:

1000Z = 2.XXXXX (again the X's dont matter)
Hence,
Z = 2.XXXXX / 1000
Or
Z = .002XXXX

So the hundredth digit of Z is 0. Sufficient Again.

Therefore the answer is D.
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by simplyjat » Mon May 05, 2008 12:59 am
jain0069 wrote:I think the answer is D.

Here's how..

1. The tenth digit of 100Z is 2.

Therefore:

100Z = .2XXXXXX (the X's dont matter)
Hence,
Z = .2XXXX / 100
Or
Z = .002XXXXX

So the hundredth digit of Z is 0. Sufficient.

2. The unit digit of 1000Z is 2. This is basically saying the same thing as statement 1. However, just taking this alone:

1000Z = 2.XXXXX (again the X's dont matter)
Hence,
Z = 2.XXXXX / 1000
Or
Z = .002XXXX

So the hundredth digit of Z is 0. Sufficient Again.

Therefore the answer is D.
You are wrong in assuming
100Z = .2XXXXXX
actually it should be
100Z = XXXX.2XXXXXX
simplyjat
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by jain0069 » Mon May 05, 2008 1:02 am
Jeez... *** Slap across the face ***... Thanks dude... Just tells me why I am so bad at DS eh ;)...

Note to self: Will always triple and quadruple check my answers before posting again...

Thanks for pointing out the mistake in my reasoning though...
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by simplyjat » Mon May 05, 2008 1:16 am
jain0069 wrote:Jeez... *** Slap across the face ***... Thanks dude... Just tells me why I am so bad at DS eh ;)...

Note to self: Will always triple and quadruple check my answers before posting again...

Thanks for pointing out the mistake in my reasoning though...
Don't be harsh on yourself, DS just requires some practice and patience.
simplyjat
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by antyagi » Mon May 05, 2008 2:15 am
I could not get the solution of the problem.

Can someone please explain the final answer of the problem please ?

Is it E ?
Thanks,
Ankur Tyagi
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Re: GMAT prep decimal

by doclkk » Tue Jul 07, 2009 9:40 pm
arorag wrote:What is the hundredth digit of the decimal Z?
1. The tenth digit of 100Z is 2
2. The unit digit of 1000Z is 2
E for sure

1. Doesn't tell you hundreths
2. Doesn't tell you hundreths

What else is there to consider?
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by abhinav85 » Wed Jul 08, 2009 9:57 am
IMO B

What is the OA arorag?
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by karthikpandian19 » Mon May 14, 2012 12:01 am
OA is E,

Can any GMAT EXPERT provide detailed explanation for this as my answer is tending towards A
Please clarify
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by eagleeye » Mon May 14, 2012 12:32 am
All right, I am going to settle this debate. btw, the correct answer is E. Here's how.

"What is the hundredth digit of the decimal Z?
1. The tenth digit of 100Z is 2
2. The unit digit of 1000Z is 2"

Let Z =abcd.efgh (where a,b,c,d,e,f,g,h are all integers) (we can go farther on each side, lets just assume this without loss of much generality). The hundredth digit here is f; if we can determine d either from 1 or 2 or both, the answer won't be E.

Now:
1. 100Z = abcdef.gh; The tenth digit is 2. So, g = 2.
therefore, 100Z=abcdef.2h
No, information about f, INSUFFICIENT.

2. 1000Z = abcdefg.h ; The unit digit is g again, so g = 2.
therefore, 1000Z = abcdef2.h
Again, we don't know what f is, INSUFFICIENT.

Now let's consider them together. Both equations give the same information, i.e. g = 2. Hence C is not a possibility as well. Therefore the correct answer is E.

Point to note: if we were not given the same information (g = 2) in the two equations, we might have been able to find f by subtracting the two equations, or substituting.

Let me know if this helps :)
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by GmatKiss » Mon May 14, 2012 3:32 am
IMO: E
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by meh » Sun Jan 12, 2014 6:07 am
If it is asking for what is the hundredths digit of decimal z, isn't z just a digit between 0-9? In that case, isn't isn't any other digit besides the units digit of z=0? e.g. z= 09.00?

Let's assume z=9

1) 100z = 900.00; tenths digit = 0
2) 1000z = 9000.00; units digit = 0

D both alone are sufficient.
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