Brian@VeritasPrep wrote:Great question with a lot of strategic value - thanks for sharing!
Here's where Data Sufficiency strategy comes in. Statement 2 alone looks pretty useless. I sort of already assumed that B was two digits, so why are they telling me that? If you read those pretty bland/useless statements by thinking "Why Are You Here?", they often tell you something really important - in this case, it's telling me that I don't have to use a number B that's in the teens...I could use a single digit number like 08 or 09. Well, that allows for 80-08 = 72 - another possibility that shows me that statement 2 alone is not sufficient. I need both to finally arrive at 91-19. So the answer is C, and I learned that by trying to determine why statement 2 even existed.
Aren't we reading the question incorrectly here
1) statement ambiguous... says
difference of i.e., 70 < |A-B| < 80
if this is correct then from 1) & 2) A could be 19 or 91.
Further more the question asks what are the digits of A?
in general someone will answer 1 & 9 or one may say 9 & 1. (place value not given importance here )
so answer is C.
I don't think A=91
correct me if I am wrong...
i used this general method to solve, much easier than trying numbers i think
x and y = digits
so
A = 10X + Y
B = 10Y + X
1) 70 < difference < 80
|A-B| = 9|X-Y|
therefore, 70 < 9|X-Y| < 80
gives X-Y = 8
possible values 9,1 or 8,0
both satisfy so INSUFFICIENT
2) B is 2 digit number
INSUFFICIENT
1) & 2) together
8,0 = get out mate
only remains 1,9
so answer C
. But ya this was a bit hard.
