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Official Guide 12th edition Problem no:65

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Official Guide 12th edition Problem no:65

by Touseef » Mon Aug 01, 2011 6:14 am
How many integers are there between, but not
including, integers r and s?

(1) s - r = 10
(2) There are 9 integers between, but not including,
r + 1 and s + 1

The Answer Explanation given in the OG takes all the numbers between 'r' and 's' as Consecutive integers,but is nowhere stated in the Question that these are consecutive integers.

Can anyone explain me the right approach to this problem?
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Source: — Data Sufficiency |
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by bblast » Mon Aug 01, 2011 6:27 am
Hi,

I had the same doubt that u have posted when I attempted this question some time back.

However in hindsight its actually a genuine trap.

To prove it just ask yourself.
how many integers are there between 10 and 20 ? We don't need to mention that we are considering consecutive integers, do we ?
Cheers !!

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by kmittal82 » Mon Aug 01, 2011 6:39 am
bblast wrote:Hi,

I had the same doubt that u have posted when I attempted this question some time back.

However in hindsight its actually a genuine trap.

To prove it just ask yourself.
how many integers are there between 10 and 20 ? We don't need to mention that we are considering consecutive integers, do we ?
>how many integers are there between 10 and 20
4 even integers
5 odd integers
9 consecutive integers

So, do you think its safe to assume if the question just asks for integers, it include all types of integers? The perils of the GMAT...
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by Touseef » Mon Aug 01, 2011 6:39 am
Thanks dude....I get it now
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by GmatKiss » Mon Aug 01, 2011 9:41 am
IMO:C what is OA?
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by HeintzC2 » Mon Aug 01, 2011 1:24 pm
The question asks for "How many integers", the term Integer covers even, odd, and consecutive integers.

for (1) s-r = 10; using easy numbers s = 11, r = 1, so s-r=10. There are 9 integers between 1 and 11 (2,3,4,5,6,7,8,9,10). Sufficient.

for (2), there are 9 integers between, but not including r+1 and s+1. Since we know already there are 9 integers between 11 and 1, we can reuse these same numbers.
therefore, r-1 and 0 and s-1 = 10. since we just subtracted 1 from both ends of our group, the number of integers within the group stays the same. there are 9 integers between 0 and 10. Sufficient.

Answer is D
Touseef wrote:How many integers are there between, but not
including, integers r and s?

(1) s - r = 10
(2) There are 9 integers between, but not including,
r + 1 and s + 1

The Answer Explanation given in the OG takes all the numbers between 'r' and 's' as Consecutive integers,but is nowhere stated in the Question that these are consecutive integers.

Can anyone explain me the right approach to this problem?
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by bblast » Mon Aug 01, 2011 9:11 pm
@ tauseef- glad it helped

@ mittal- you have to be careful what inference you make from the wording of the question.
Cheers !!

Quant 47-Striving for 50
Verbal 34-Striving for 40

My gmat journey :
https://www.beatthegmat.com/710-bblast-s ... 90735.html
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https://www.beatthegmat.com/ways-to-bbla ... 90808.html
How to prepare before your MBA:
https://www.youtube.com/watch?v=upz46D7 ... TWBZF14TKW_
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