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Re: Number again... [#permalink]
08 Jun 2007, 14:13
x and y are 2-digt integers. What is the difference between two tens' digit? 1). x-y=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?
x and y are 2-digt integers. What is the difference between two tens' digit?
2). Units' digit of x minus the units' digit of y is greater than 3
x = AB
Y = CD
1) Stated that X-Y = 27; thus, we know that B-D=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 A-C. This statement is INSUFFICIENT.
2) Stated that B-D > 3. We only know the unit digit substraction, we don't know the tens digits; thus, INSUFFICIENT.
Together, we know that B-D > 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, A-C must be 2. SUFFICIENT.