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Can't figure out this question - No solution provided

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by prc41247 » Tue Oct 04, 2016 3:01 pm
Just took the free practice exam on Babson.edu, this question has left me wondering how they got the correct answer. Either there is something I'm not seeing or it is a typo.

If 3<x<6<y<10, then what is the greatest possible positive integer difference of x and y?

A) 3
B) 4
C) 5
D) 6
E) 7

I chose C, but the correct answer is D
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Source: — Problem Solving |

by Brent@GMATPrepNow » Tue Oct 04, 2016 3:19 pm
prc41247 wrote:Just took the free practice exam on Babson.edu, this question has left me wondering how they got the correct answer. Either there is something I'm not seeing or it is a typo.

If 3<x<6<y<10, then what is the greatest possible positive integer difference of x and y?

A) 3
B) 4
C) 5
D) 6
E) 7

I chose C, but the correct answer is D
We want to MAXIMIZE y and MINIMIZE x

If, it were the case that 3 < x < 6 < y < 10, then the maximum value for y would be 10, and the minimum value of x would be 3
Here, the difference = 10 - 3 = 7
HOWEVER, y cannot equal 10 and x cannot equal 3. So, the difference of x and y cannot be 7. ELIMINATE E

What about answer choice D?
Well, if y = 9.5 and x = 3.5, the difference is 6

Done!
Answer: D
Brent Hanneson - Creator of GMATPrepNow.com
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by prc41247 » Tue Oct 04, 2016 3:34 pm
Ahh I see now. I got caught up on, 'integer difference', and assumed that x and y had to be integers - but it only meant that x - y had to be an integer.

Thanks!
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