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vijaynarayanan
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Vijay,
Just to know what is the source of this question?
Numbers
This topic has expert replies
Source: Beat The GMAT — Data Sufficiency |
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kvcpk
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x-y = 9k ???vijaynarayanan wrote:
Kindly help me solve.
Correct Answer: A
let x= 10a +b
y = 10b+a
x-y = 9(a-b)
a and b are integers. So x-y is a multiple of 9.
SUFF
x = 10a1+b1
y = 10a2+b2
a1 = b1+2
a2 = b2-2
x-y = 11b1+20 - 11b2-20
=11(b1-b2)+40
=40+11 or 40 +22 or 40+33 or 40+44 or.....
Cannot be multiple of 9
pick A
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kvcpk
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Yeah you are right.. But, x and y are integers between 10 and 99.selango wrote:Praveen buddy.....
40+77=117 is divisible by 9.
So maximum difference among them is 99-10 =89
So x-y cannot be 117.
for x-y we will get 51, 62, 73, 84 only. Forgot to mention this in above post
None of these are divisible by 9.
Hope this helps!!
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kvcpk
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oops.. Forgot the possibility that b1-b2 could be negative also.
So, 40-11, 40-22,40-33 are also possible.
-> 29,18,7
18 is divisible by 9
Hence we get conflict of YES and NO.
hence stmt2 is not sufficient.
PICK A.
So, 40-11, 40-22,40-33 are also possible.
-> 29,18,7
18 is divisible by 9
Hence we get conflict of YES and NO.
hence stmt2 is not sufficient.
PICK A.
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clock60
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all is said about this problem, my answer also A and my two cents
is (x-y)/9=integer
(1) x=10a+b, y=10b+a. so
x-y=10a+b-10b-a=9a-9b=9(a-b)-must be divisible by 9
so sufficient
(2) x=10a+(a-2)=11a-2
y=10b+(b+2)=11b+2
x-y=11a-2-11b-2=11(a-b)-4, now let us check
if a-b=1, 11-4=7 not divisible by 9
a-b=2, 11*2-4=18 divisible by 9
a-b=3 11*3-4=29 not divisible by 9
as we have yes and no answers st2 insufficient
so A
is (x-y)/9=integer
(1) x=10a+b, y=10b+a. so
x-y=10a+b-10b-a=9a-9b=9(a-b)-must be divisible by 9
so sufficient
(2) x=10a+(a-2)=11a-2
y=10b+(b+2)=11b+2
x-y=11a-2-11b-2=11(a-b)-4, now let us check
if a-b=1, 11-4=7 not divisible by 9
a-b=2, 11*2-4=18 divisible by 9
a-b=3 11*3-4=29 not divisible by 9
as we have yes and no answers st2 insufficient
so A
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singhpreet1
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i beg to differ...it says that x and y are integers between 10 and 99, not that their difference is between 10 and 99. so 40+77 is a valid argument in my opinion.kvcpk wrote:Yeah you are right.. But, x and y are integers between 10 and 99.selango wrote:Praveen buddy.....
40+77=117 is divisible by 9.
So maximum difference among them is 99-10 =89
So x-y cannot be 117.
for x-y we will get 51, 62, 73, 84 only. Forgot to mention this in above post
None of these are divisible by 9.
Hope this helps!!
Preet
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kvcpk
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Hi Preet,singhpreet1 wrote: i beg to differ...it says that x and y are integers between 10 and 99, not that their difference is between 10 and 99. so 40+77 is a valid argument in my opinion.
Preet
if x an y are integers between 10 and 99, themaximum difference x-y can be when
x is maximum and y is minimum
Maximum x possible is99, minimum y possible is 10
difrence is 99-10 = 89.
SO maximumvalue ofx-y is 89.
Hope this helps!!
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singhpreet1
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that is true...i need to convince myself to do the maximum- minimum concept to get this straight.kvcpk wrote:Hi Preet,singhpreet1 wrote: i beg to differ...it says that x and y are integers between 10 and 99, not that their difference is between 10 and 99. so 40+77 is a valid argument in my opinion.
Preet
if x an y are integers between 10 and 99, themaximum difference x-y can be when
x is maximum and y is minimum
Maximum x possible is99, minimum y possible is 10
difrence is 99-10 = 89.
SO maximumvalue ofx-y is 89.
Hope this helps!!
thanks.
Preet
