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DS problem on perm&combination

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DS problem on perm&combination

by knight247 » Thu Jun 23, 2011 10:40 am
In a room, there were 10 sibling pairs. A few individuals moved out of the room. Is the number
of sibling pairs remaining in the room greater than 4?
(1)The number of individuals who moved out of the room was greater than 5.
(2)The number of individuals who moved out of the room was less than 12.

(A)Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient to answer the question asked.
(B)Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient to answer the question asked.
(C)BOTH statements (1) and (2) TOGETHER are sufficient to answer the question asked, but NEITHER statement ALONE is sufficient.
(D)EACH statement ALONE is sufficient to answer the question asked.
(E)Statements (1)' and (2) TOGETHER are NOT sufficient to answer the question asked, and additional data are needed.

Detailed explanations would be appreciated
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by Frankenstein » Thu Jun 23, 2011 10:48 am
Hi,
From(1): Let the number of individuals moved be 6.
If none of the 6 individuals moved are siblings, then the number of siblings left in room is 4
If the 6 individuals moved are 3 pairs of siblings, then the number of siblings left in room is 7(greater than 4)
Not sufficient

From(2):The above case can be used for this as well
Not sufficient
Both(1)&(2): same case
Not sufficient

Hence, E
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by knight247 » Mon Jun 27, 2011 10:36 am
I don't agree frank. Statement 1 is definitely insufficient. Lets consider statement 2

(2)The number of individuals who moved out of the room was less than 12.

Lets consider the number who moved out as 11. If the 11 ppl consist of 5 pairs of siblings and 1 other person then the number of sibling pairs left is 4. Which is not greater than 4. So it gives us a clear NO

Assuming none of those who moved out to be siblings then there isn't a single sibling pair left. So even this assumption gives us a clear NO.

So as per me the answer is B
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by Frankenstein » Mon Jun 27, 2011 10:43 am
knight247 wrote:I don't agree frank. Statement 1 is definitely insufficient. Lets consider statement 2

(2)The number of individuals who moved out of the room was less than 12.

Lets consider the number who moved out as 11. If the 11 ppl consist of 5 pairs of siblings and 1 other person then the number of sibling pairs left is 4. Which is not greater than 4. So it gives us a clear NO

Assuming none of those who moved out to be siblings then there isn't a single sibling pair left. So even this assumption gives us a clear NO.

So as per me the answer is B
Okay, what if only 1 individual moved out?
The number of sibling pairs remaining in room is 9. So, the answer is Yes.
That is the reason we cannot say for certain whether the answer is Yes or No.
Hence, st(2) is insufficient as well.
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by amit2k9 » Tue Jun 28, 2011 11:53 pm
a people left can be 6 - 19. not sufficient.

b people left can be 1-11. pairs will be =4 and >4. not sufficient.

a+b
5< people left <12 meaning =4 pair and > 4 pair. Not sufficient.

E it is.
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by sunilrawat » Wed Jun 29, 2011 12:25 am
you cannot judge by only one possibility, try other nos. also and u get an uncertain situation for (2) as well

knight247 wrote:I don't agree frank. Statement 1 is definitely insufficient. Lets consider statement 2

(2)The number of individuals who moved out of the room was less than 12.

Lets consider the number who moved out as 11. If the 11 ppl consist of 5 pairs of siblings and 1 other person then the number of sibling pairs left is 4. Which is not greater than 4. So it gives us a clear NO

Assuming none of those who moved out to be siblings then there isn't a single sibling pair left. So even this assumption gives us a clear NO.

So as per me the answer is B
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by testprepDublin » Wed Jun 29, 2011 5:05 am
In a room, there were 10 sibling pairs. A few individuals moved out of the room. Is the number
of sibling pairs remaining in the room greater than 4?

Think about the minimum and maximum before looking at the statements.

We would need at least 13 to leave to guarantee 4 sibling pairs not left.
We would need fewer than 7 to leave to guarantee at least 4 sibling pairs left.


(1)Leavers>5.
but fewer than 7 or more than 13?
Insufficient.
(2)Leavers<12.
but more or fewer than 7?
Insufficient.

(1)&(2) 5<Leavers<12
but more or fewer than 7?
Insufficient.
Deirdre at testprepdublin.com
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