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4 DS questions to be solved

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4 DS questions to be solved

by charmaine » Sun Sep 14, 2008 3:05 pm
q. 1
if x and y are nonzero integers, is 18 a factor of xy^2?
1) x is a multiple of 54
2) y is a multiple of 6

ans. D

q2

in the xy plane, does the point (a,b) lie above the line x=y?
1) a=2
2) b= a +2

ans. B



(x=y means its parallel right ???)

q3

if n is a positive integer, what is the value of n ?
1) when n is divided by 3, the remainder is 2
2) when n ^2 is divded by 3, the remainder is 1

ans. E

q4

if lm+4l=2 what is the value of m ?
1) m<0
2) m^2+8m +12= 0

ans. E
( i think its A cz from statement 1 we get that it is negative ...i am not sure )

thanks you guys ..its obvious i am still stuck on DS questions that have to do with divisibility, multiplication and remainder ...thanks :) appreciated
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Re: 4 DS questions to be solved

by Sunny22uk » Sun Sep 14, 2008 3:36 pm
charmaine wrote:q. 1
if x and y are nonzero integers, is 18 a factor of xy^2?
1) x is a multiple of 54
2) y is a multiple of 6
A) x is a multiple of 54 which can be rewritten as 18*3, hence 18 is a factor of xy^2 SUFFICIENT
B) since y=6, y^2=36, 18 is a factor of 36, SUFFICIENT
Thus the answer is D
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Re: 4 DS questions to be solved

by Sunny22uk » Sun Sep 14, 2008 3:47 pm
charmaine wrote:q. 1
q2

in the xy plane, does the point (a,b) lie above the line x=y?
1) a=2
2) b= a +2
x=y is straight line which goes across 1st and 3rd quadrant and through the origin(since y=x)
a) a=2, we don't know b, NOT SUFFICIENT
b) b=a+2 is sufficient for all values of (a,b) and it will be above the line x=y(e.g. point 2,4 is above the line y=x)

Wish I could draw a quick diagram for you.
Also, Please don't post the answer for questions. You can use the Spoiler tag to hide the answers
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Re: 4 DS questions to be solved

by Sunny22uk » Sun Sep 14, 2008 3:54 pm
charmaine wrote:q. 1
q3
if n is a positive integer, what is the value of n ?
1) when n is divided by 3, the remainder is 2
2) when n ^2 is divided by 3, the remainder is 1
1) A cannot be sufficient because there can be an infinite number of integers which can be divided by 3 and the remainder will be 1 e.g. 5,8,11.......
2)B Can be eliminated right away for the same reason, there are infinite values for n for this condition e.g. 2,5, 8...
3) taking them together we have commone values(e.g. 5,8 ) and we don't havea definite value of n
Hence answer should be E
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Re: 4 DS questions to be solved

by Sunny22uk » Sun Sep 14, 2008 3:59 pm
charmaine wrote: if lm+4l=2 what is the value of m ?
1) m<0
2) m^2+8m +12= 0
A) For m<0 and for lm+4l=2, there are 2 possible values for m i.e. -6,-2
Hence NOT SUFFICIENT
B)the second is a quadratic equation, the 2 roots are -6,-2
Hence NOT SUFFICIENT
C) Combining 1 and 2, we still have 2 values=-6, -2
Hence NOT SUFFICIENT

Answer is E
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by charmaine » Sun Sep 14, 2008 4:19 pm
thanks sunny ..u hv been a grt help ..will use the spoiler tag nxt time :)
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Re: 4 DS questions to be solved

by charmaine » Sun Sep 14, 2008 7:38 pm
Sunny22uk wrote:
charmaine wrote:q. 1
if x and y are nonzero integers, is 18 a factor of xy^2?
1) x is a multiple of 54
2) y is a multiple of 6
A) x is a multiple of 54 which can be rewritten as 18*3, hence 18 is a factor of xy^2 SUFFICIENT
B) since y=6, y^2=36, 18 is a factor of 36, SUFFICIENT
Thus the answer is D
i am sorry but if y is a multiple of 6 ...how can y be 6 ??shouldnt it be bigger than 6 ??/thanks
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Re: 4 DS questions to be solved

by Sunny22uk » Sun Sep 14, 2008 7:54 pm
charmaine wrote:
Sunny22uk wrote:
charmaine wrote:q. 1
if x and y are nonzero integers, is 18 a factor of xy^2?
1) x is a multiple of 54
2) y is a multiple of 6
A) x is a multiple of 54 which can be rewritten as 18*3, hence 18 is a factor of xy^2 SUFFICIENT
B) since y=6, y^2=36, 18 is a factor of 36, SUFFICIENT
Thus the answer is D
i am sorry but if y is a multiple of 6 ...how can y be 6 ??shouldnt it be bigger than 6 ??/thanks
My bad, y is not equal to 6 but is a multiple of 6 which means it can be 6, 36, 216 and so on...y^2 in turn will be a multiple of 36,thus 18 will be a factor of xy^2.When I said y=6, I just took a sample value.
Let me know if you have any questions.
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by charmaine » Sun Sep 14, 2008 8:23 pm
thanks sunny ...see that u r takin ur gmat end of sept ...am taking it next week ...good luck to u :) and thanks for all ur help ...really appreciate it :)))
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by Sunny22uk » Sun Sep 14, 2008 8:33 pm
charmaine wrote:thanks sunny ...see that u r takin ur gmat end of sept ...am taking it next week ...good luck to u :) and thanks for all ur help ...really appreciate it :)))
Hey good luck with it. Kill the Beast.
You cannot discover new oceans unless you have the courage to loose sight of the shore.
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