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DS problem. Stuck on statement (2).

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by aman88 » Wed Dec 12, 2012 9:41 am
Q: If √x is an integer, what is the value of √x?
(1) 11<x<17
(2) 2<√x<5

I understood Statement (1) but can someone please explain statement (2)?

2<√x<5 -> Here √x can be √3 or √4 and the question stem says √x is an integer. So from √3 or √4, only √4 is an integer which is 2. Why is D not the right answer but A?

Thanks.
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Source: — Data Sufficiency |

by Brent@GMATPrepNow » Wed Dec 12, 2012 9:48 am
aman88 wrote:Q: If √x is an integer, what is the value of √x?
(1) 11<x<17
(2) 2<√x<5

I understood Statement (1) but can someone please explain statement (2)?

2<√x<5 -> Here √x can be √3 or √4 and the question stem says √x is an integer. So from √3 or √4, only √4 is an integer which is 2. Why is D not the right answer but A?

Thanks.
The problem is with the part in green.

If √x is an integer, and 2 < √x < 5, we know that √x can be either 3 or 4.

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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by Brent@GMATPrepNow » Wed Dec 12, 2012 9:53 am
aman88 wrote:Q: If √x is an integer, what is the value of √x?
(1) 11<x<17
(2) 2<√x<5
Target question: What is the value of √x?

Given: √x is an integer

Statement 1: 11 < x < 17

If √x is an integer, then x must be a perfect square.
This tells us that x must equal 16, which means √x must equal 4
Since we can answer the target question with certainty, statement 1 is SUFFICIENT

Statement 2: 2 < √x < 5
Since √x is an integer, there are two possible cases to consider:
Case a: √x = 3
Case b: √x = 4
Since we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENT

Answer = A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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