Counting integers

[sperez4mba]

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

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Counting numbers between r and s (including both of them) I'd say the count is s - r + 1
and using (1) s - r = 10 then between them there are 11 integers but since the stem question
asks r and s not to be included then, 11 - 2 = 9.

As I understand (2) it says integers between s + 1 and r + 1 not including those is 9
therefore 9 is the number of integers between r and s including them so, not including them
as the stem question asks, I'd say the number of integers between r and s is 9 - 2 = 7.

Since the statements contradict each other it'd make me think there is a mistake in
the reasoning I applied.

Could someone please help?

thanks

[shankar.ashwin]

Assume numbers, it would be clear.
In (B) - Let s+1=20 r+1=10

There are 9 numbers between (r+1) and (s+1)
Here; s=19 and r=9. Still s-r=10 which is the same as statement (1)

[GmatMathPro]

As I understand (2) it says integers between s + 1 and r + 1 not including those is 9
therefore 9 is the number of integers between r and s including them so, not including them
as the stem question asks, I'd say the number of integers between r and s is 9 - 2 = 7.

thanks

If there are 9 integers between s+1 and r+1, there should also be 9 integers between r and s. For example. Let r+1=1 and s+1=11. There are 9 numbers in between: 2,3,4,5,6,7,8,9,10. Now, r=0, and s=10. There are also 9 integers in between 0 and 10: 1,2,3,4,5,6,7,8,9. Adding 1 just shifts everything by 1, but it doesn't change the distance between the numbers, which is the crucial thing to know here.

[HSPA]

I think the answer is only B and not A.

[GmatMathPro]

I think the answer is only B and not A.

because....

[HSPA]

I think the answer is only B and not A.

because....

s-r is giving us the range but not the number of elements in the set.

[shankar.ashwin]

If its a question on sets, what you say makes sense. But here they just ask for the number of integers between r and s. So there's no range or number of elements here. Its just integers between r and s.

I think the answer is only B and not A.

because....

s-r is giving us the range but not the number of elements in the set.

[HSPA]

makes sense.. I guess I mistook the stem

If its a question on sets, what you say makes sense. But here they just ask for the number of integers between r and s. So there's no range or number of elements here. Its just integers between r and s.

I think the answer is only B and not A.

because....

s-r is giving us the range but not the number of elements in the set.