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by prachi18oct » Wed Jun 17, 2015 1:40 pm
If a is a positive integer less than 3 and b is a positive integer less than 11, what is the value of the decimal expression of a/b when rounded to the nearest tenth?

(1) When the decimal expression of a/b is rounded to the nearest tenth the value of the tenths digit is 1.
(2) When the decimal expression of a/b is rounded to the nearest ten-thousandths the value of the ten-thousandths digit is 9.

A)Statement (1) ALONE is sufficient, but statement (2) is not sufficient.
B)Statement (2) ALONE is sufficient, but statement (1) is not sufficient.
C)BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D)EACH statement ALONE is sufficient.
E)Statements (1) and (2) TOGETHER are NOT sufficient.
Last edited by prachi18oct on Thu Jun 18, 2015 6:22 am, edited 1 time in total.
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by theCEO » Wed Jun 17, 2015 5:15 pm
prachi18oct wrote:If a is a positive integer less than 3 and b is a positive integer less than 11, what is the value of the decimal expression of when rounded to the nearest tenth?

(1) When the decimal expression of is rounded to the nearest tenth the value of the tenths digit is 1.
(2) When the decimal expression of is rounded to the nearest ten-thousandths the value of the ten-thousandths digit is 9.

A)Statement (1) ALONE is sufficient, but statement (2) is not sufficient.
B)Statement (2) ALONE is sufficient, but statement (1) is not sufficient.
C)BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
D)EACH statement ALONE is sufficient.
E)Statements (1) and (2) TOGETHER are NOT sufficient.
The statements are missing some information.

(1) When the decimal expression of ? is rounded to the nearest tenth the value of the tenths digit is 1.
(2) When the decimal expression of ? is rounded to the nearest ten-thousandths the value of the ten-thousandths digit is 9
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by DavidG@VeritasPrep » Thu Jun 18, 2015 5:09 am
what is the value of the decimal expression of when rounded to the nearest tenth?
Should this be "what is the value of the decimal expression of a/b when rounded to the nearest tenth?"
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by prachi18oct » Thu Jun 18, 2015 6:23 am
DavidG@VeritasPrep wrote:
what is the value of the decimal expression of when rounded to the nearest tenth?
Should this be "what is the value of the decimal expression of a/b when rounded to the nearest tenth?"
Yes, I have edited my post.
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by DavidG@VeritasPrep » Thu Jun 18, 2015 7:08 am
If 'a' is a positive integer less than 3, 'a' can be 1 or 2.
IF 'b' is a positive integer less than 11, 'b' can be anything between 1 and 10, inclusive.

If 'a' is 1, then a/b could be: 1/1; 1/2; 1/3; etc....
If 'a' is 2, then a/b could be 2/1; 2/2; 2/3;, etc.

S1:
a/b could be 1/10, which is .1; rounded to nearest tenth, still .1
a/b could be 1/9, which is .11111; rounded to nearest tenth = .1
a/b could be 1/8, which is .125, rounded to the nearest tenth = .1
a/b could be 1/7, which is .14286, rounded to the near tenth = .1

No matter what, a/b rounded to nearest tenth will be .1, so Statement 1 alone is sufficient;

S2:
a/b can only be 1/7, which is .14286; rounded to nearest ten thousandth = .1429. Rounded to nearest tenth = .1; This is the only possibility. Statement 2 alone is sufficient.

Either statement alone is sufficient. Answer is D.

Strange question.
Last edited by DavidG@VeritasPrep on Thu Jun 18, 2015 9:45 am, edited 1 time in total.
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by Ian Stewart » Thu Jun 18, 2015 9:40 am
Just to find a fraction a/b here that works with Statement 2, you need to expand 1/7 to five decimal places, which is not the kind of thing you'd ever need to do on a real GMAT question. So this isn't a realistic problem, and I wouldn't worry about it.

And one small correction:
DavidG@VeritasPrep wrote:
a/b could be 1/7, which is .14386, rounded to the near tenth = .1
1/7 is equal to 0.142857...
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by DavidG@VeritasPrep » Thu Jun 18, 2015 9:47 am
Thanks, Ian. Just edited. And I agree that this isn't something you'd see on the test.
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by nikhilgmat31 » Fri Jun 26, 2015 3:32 am
why possibility of a=3 is not considered

a=2
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by theCEO » Fri Jun 26, 2015 3:59 am
nikhilgmat31 wrote:why possibility of a=3 is not considered

a=2
a=3 is not considered because the quetion states that a is a positive integer less than 3
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by Matt@VeritasPrep » Mon Jun 29, 2015 4:24 pm
Ian Stewart wrote:Just to find a fraction a/b here that works with Statement 2, you need to expand 1/7 to five decimal places, which is not the kind of thing you'd ever need to do on a real GMAT question
Well, I dunno. Sevenths have interesting cyclic properties (1/7 = .142857..., 2/7 = .285714..., 3/7 = .428571..., etc.) and if I were a testwriter I'd consider using them. Just because there aren't OG questions testing this doesn't mean there *couldn't* be.
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by Ian Stewart » Tue Jun 30, 2015 11:00 pm
Matt@VeritasPrep wrote:
Well, I dunno. Sevenths have interesting cyclic properties (1/7 = .142857..., 2/7 = .285714..., 3/7 = .428571..., etc.) and if I were a testwriter I'd consider using them. Just because there aren't OG questions testing this doesn't mean there *couldn't* be.
I do not base my opinions about the scope of the GMAT solely on what is found in the OG, and I do not understand why you'd make that insinuation.

I do base those opinions on the 5,000-10,000 official Quant questions I've seen. I've seen exactly two real questions where a test taker might contemplate using long division to produce a repeating decimal. In both you could avoid long division if you knew the decimal expansion of 1/9, and in both, the decimal repeated after three digits. When I say the GMAT does not test whether you can expand a repeating decimal to five places, or whether you know the decimal expansion of 1/7 to five places, I'm basing that on looking at every published official question I've been able to find from the last fifteen years. If you have evidence to the contrary, I'd be interested in seeing it.

Nor, incidentally, do I think they could test such things, even if they haven't in the past, but I'd have to get into a long technical discussion to justify that. But in short, GMAT question writers cannot simply test whatever mathematical properties they find interesting. Questions need to meet the assumptions of Item Response Theory, and need to differentiate clearly among test takers at different ability levels. I have good reasons to think questions about long division would not do that.

And yes, the GMAT does test cyclic properties, but it does so in other ways - in word problems with repeating patterns of coloured tiles, in units digits questions with exponents, in sequence questions where the sequence loops.
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by nikhilgmat31 » Tue Jun 30, 2015 11:26 pm
if a=1 & b=7 a/b = .1429

a =2 is not considered because if a=2 & b=7 a/b = .2857
leads to ten thousandth digit =7 but in statement 2 says ten thousand digit is 9.
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