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Director
Joined: 25 Oct 2006
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x and y are 2digt integers. What is the difference between [#permalink]
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08 Jun 2007, 14:31
This topic is locked. If you want to discuss this question please repost it in the respective forum. x and y are 2digt integers. What is the difference between two tens' digit?
1). xy=27
2). Units' digit of x minus the units' digit of y is greater than 3.
Answer with explanation please,
Any template or thoughts on how to attack this kinda problem.



Director
Joined: 12 Jun 2006
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Re: Number again... [#permalink]
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08 Jun 2007, 15:13
priyankur_saha@ml.com wrote: x and y are 2digt integers. What is the difference between two tens' digit? 1). xy=27 2). Units' digit of x minus the units' digit of y is greater than 3. Answer with explanation please, Any template or thoughts on how to attack this kinda problem. I'd have to go with C. I picked #s
1 and 2 insufficient.
While picking #s it seemed that the difference b/w the units digit of x and y was either negative 3 or +ve 7. When the difference b/w the units digit was ve the diff b/w the tens was 3. When the diff b/w the units digit was 7 the diff b/w the tens was 2. Anyone have a better method?



Director
Joined: 26 Feb 2006
Posts: 899

Re: Number again... [#permalink]
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08 Jun 2007, 17:02
priyankur_saha@ml.com wrote: x and y are 2digt integers. What is the difference between two tens' digit? 1). xy=27 2). Units' digit of x minus the units' digit of y is greater than 3. Answer with explanation please, Any template or thoughts on how to attack this kinda problem.
suppose if
if x = 49 and y = 22, x  y = 27 and the difference between tens digits of x and y is 2.
if x = 40 and y = 13, x  y = 27 and the difference between tens digits of x and y is 3.
I got E. did i miss anything????????????/



Manager
Joined: 18 Apr 2007
Posts: 120

I agree with Himalaya... I got E.
From stmt [1] we know that the difference between the tens digit can only be 3 or 2. Insufficient.
Stmt [2] tells us nothing because we already know that the units digit of x minus the units digit of y is 7, which is greater than 3. Insufficient.
Putting both together gives us nothing.
Answer: E



Director
Joined: 13 Mar 2007
Posts: 543
Schools: MIT Sloan

go with C
st1  either 2 or 3 INSUFF
st2  Insuff by itself
st1 and st2  only 2 is poss SUFF



CEO
Joined: 17 May 2007
Posts: 2950

lets say x = AB y = CD
According to 1)
AB
CD

27
We have to find A  C
Now there two possibilities 3 and 2.
So A is insufficient
According to 2
BD > 3 which is excellent news. Because it tells us that there is no carry over from the A to B in order to subtract D. Thus It is sufficient to know that AC = 2.
Hence answer is C .



Director
Joined: 25 Oct 2006
Posts: 635

In my copy I've got the answer E, but not sure whether it's OA!! Thanks for the discussion....



Manager
Joined: 23 Dec 2006
Posts: 134

Alternatively, let 10u+t and 10m+n denote our two numbers
1) says 10u+t  (10m+n) = 27
2) says tn > 3
expand 1: 10(um) + (t  n) = 27
2710(um) = t  n
2710(um) > 3
24 > 10(um)
Now, we only know that 10(um) needs to be LARGER than 24, but we don't have an upper bound. Therefore, E.



Director
Joined: 25 Oct 2006
Posts: 635

sludge wrote: Alternatively, let 10u+t and 10m+n denote our two numbers
1) says 10u+t  (10m+n) = 27
2) says tn > 3
expand 1: 10(um) + (t  n) = 27
2710(um) = t  n
2710(um) > 3
24 > 10(um)
Now, we only know that 10(um) needs to be LARGER than 24, but we don't have an upper bound. Therefore, E.
Thanks, I proceeded in this way...



Manager
Joined: 07 May 2007
Posts: 178

Let x=10m+n
and y=10p+q
From 1, xy = 10(mp)+(nq) = 27
This can be expressed as 10*33 or as 10*2+7
So, the diff of units digits can be 7 or 3
Diff of tens digits can be 2 or 3
Second stmt says diff is greater than 3. So it has to be 7.
So Diff of tens digits should be 2
Answer is both together are suff



VP
Joined: 10 Jun 2007
Posts: 1438

x and y are 2digt integers. What is the difference between two tens' digit?
1). xy=27
2). Units' digit of x minus the units' digit of y is greater than 3
______________________________________________________
Set:
x = AB
Y = CD
1) Stated that XY = 27; thus, we know that BD=7. Therefore, the possible values for (B,D) are (0,3) (7,0) (8,1) (9,2). If (B,D) = (0,3), then we know that we have to subtract 1 from A. If (B,D) = (7,0) OR (8,1) OR (9,2), we do not substract 1 from A. This means that we cannot determine AC. This statement is INSUFFICIENT.
2) Stated that BD > 3. We only know the unit digit substraction, we don't know the tens digits; thus, INSUFFICIENT.
Together, we know that BD > 3. This eliminate the possible value of (B,D) = (0,3). Since (B,D) not equal to (0,3), we know that we don't have to substract one from A; thus, AC must be 2. SUFFICIENT.
Let me know if there is any mistake.










