GMAT Data Sufficiency Discussions

MBA GMAT
1421
OA is C.

U can calulate the range of the numbers using the inequalities, and the both x and y are +ve. So C.

Hi can u elaborate it a little more?
I am drawing the graps and find out that the entire region of the two graps coming in second quadrant making x0 so making D as answer.
I know I am wrong somewhr.
1422
Hi can u elaborate it a little more?
I am drawing the graps and find out that the entire region of the two graps coming in second quadrant making x0 so making D as answer.
I know I am wrong somewhr.


There won't be any intersection in the IInd quad. Check your equations again:lookround:

May be you are marking the regions wrong after drawing the correct lines. Put (0,0) (say) in each line and see the sign (+/-) to get the correct region on the number line.

They'll intersect in the first quad.
1423
OA is C.

U can calulate the range of the numbers using the inequalities, and the both x and y are +ve. So C.




Take 1) x-y>-2 so we have 2 unknowns and 1 equation. so 1) alone is insuff

take 2) x-2y
take both 1) and 2)
we get x-y>-2 and 2y-x>6. Solving, we get y>4 and x>2. so both are +ve real numbers hence product is always +ve. Hence C.
1424
One more

Is xy>0?

1) x-y>-2
2)x-2y
OA later


The 1st statement is x-y>-2 which can be altered to -x+y (1)

The 2nd statement is x-2y (2)

Adding both the statements we get -y4

From the 1st statement we know that x>y-2 so x is also positive

Hence the ans is C
1425

Selling price and asking price are different / aswer is c

1426

Who shaves the barber?
1) The barber shaves all those who do not shave themselves.
2) The barber shaves only those who do not shave themselves.

1427

few DS problems. Please post explanations as well as i need to find the best approach.

Are x and y both positive?
1. 2x - 2y =1
2. x/y > 1

Is x-y > |x| -y?
1. y 2. xy
The positive integers x, y, and z are such that x is a factor of y and y is a factor of z. is z even?

1. xz is even
2. y is even

1428
few DS problems. Please post explanations as well as i need to find the best approach.

Are x and y both positive?
1. 2x - 2y =1
2. x/y > 1

Is x-y > |x| -y?
1. y 2. xy
The positive integers x, y, and z are such that x is a factor of y and y is a factor of z. is z even?

1. xz is even
2. y is even


1)E
consider 1,
x-y = .5 so there are number of solns for this equation
so insuff
consider 2
not suff, as x,y can be both -ve or +ve

consider both still there is no clue of the sign

2)C
consider 1) we can have many equations satisfying the inequality. so insuff
conisder 2) we dont know whether x is +ve or y. so insuff
Consider both we know the signs and hence can solve the equation.

3)B

here y/x and z/y the question is z even?

consider 1) either x or z can be even so insuff

Consider 2) y is even so z has to be even as an odd number cannot have even factors.

So B.
1429

try the following puys:

1) Is x^y
1) a

1430
In a certain senior class, 72 percent of the male students and 80 percent of the female students have applied to college. What fraction of the students in the senior class are male?

(1) There are 840 students in the senior class
(2) 75 percent of the students in the senior class have applied to college
1431
1)E
consider 1,
x-y = .5 so there are number of solns for this equation
so insuff
consider 2
not suff, as x,y can be both -ve or +ve

consider both still there is no clue of the sign

2)C
consider 1) we can have many equations satisfying the inequality. so insuff
conisder 2) we dont know whether x is +ve or y. so insuff
Consider both we know the signs and hence can solve the equation.

3)B

here y/x and z/y the question is z even?

consider 1) either x or z can be even so insuff

Consider 2) y is even so z has to be even as an odd number cannot have even factors.

So B.


I think 2nd will be B
1432
Gatty07 Says
I think 2nd will be B



please explain??
1433
siddharthaduggirala Says
please explain??


putting values for x, y
x=5, y=-6 and x=5, y=-3
similarly, x=-3, y=5 and x=-6, y=5...all give the same result....
correct me if I am wrong....
1434
putting values for x, y
x=5, y=-6 and x=5, y=-3
similarly, x=-3, y=5 and x=-6, y=5...all give the same result....
correct me if I am wrong....



yup you are right.. i got this wrong
1435

1) Is x^y option 1 : y^2=x , then to check if x^y 2 the inequality remains the same y reverses --> no relevance
option 2 : y
so Answer is 5
------------------------------------------
2) Is 1/(a-b)
1) alet a-b = A then 1/A +A
so a-b should be definitely negative or definitely postive to get the answer.
Option 1 )a a-b Option 2) 1 a-b >1 or a-b
so Answer is 1
------------------------------------------
3) In the fraction x/y, where x and y are +v integers, what is the value of y?
1) the least common denominator of x/y and 1/3 is 6.
2) x=1

option 1 )Least common denominator of x/y and 1/3 is 6 so Y can be 2 or 6 or ..so value of y cant be found
Option 2) x = 1 who cares :biggrin: this is not relevant at all..!!
so Answer is 5
------------------------------------------
4)If x is a +ve integer and w is a -ve integer, what is the value of xw?

1) x^w= 1/2
2) w=-1

Option 1) x^w= 1/2 since w is negative. and the RHS is a 2^-x form,(2^-1)
X is a multiple of 2
2^w =1\2 w = -1
4^w =1\2 w = -1/2 ...
so on ....!!
but we know W is an integer , a negative integer so (x,w) can be only (2,-1)
so Answer is 1
------------------------------------------
5) Is x/m (m^2+n^2+k^2) = xm+yn+zk?

1) z/k = x/m
2) x/m = y/n

x*m^2+x*n^2+x*k^2) = x*m*m+y*m*n+z*m*k
x*n*n + x*k*k = y*m*n+z*m*k ? is the kostin..
option 1
z/k = x/m --> k*x =m*z
x*n*n + x*k*k = y*m*n+z*m*k -->x*n*n = y*m*n ? --> x*n =y*m ? so u cant answer from this
option 2
x/m = y/n -->m*y =x*n
x*n*n + x*k*k = y*m*n+z*m*k--> k*x =m*z ? so u cant answer from this
taking both u get x/m (m^2+n^2+k^2) = xm+yn+zk so
so Answer is 3
------------------------------------------
6)if k and n are integers is n divisible by 7?
1) n-3 =2k
2)2k+4 is divisible by 7.

option 1 : n =2k+3 --> no relevance
option 2 : 2k+4 is divisible by 7 no relevance to n
joining both n = 2k+4-1 --> 7p-1 so is not divisble by 7 hence
so Answer is 3



P.S: will add other answer in a while ..brb :lunch :biggrin:

1436
In a certain senior class, 72 percent of the male students and 80 percent of the female students have applied to college. What fraction of the students in the senior class are male?



(1) There are 840 students in the senior class

(2) 75 percent of the students in the senior class have applied to college

Let male students be M and female students be f
total students=m+f
Consider statement 1
Total 840 students i.e. m+f=840
0.72m+ .80f=students who applied for college--> this is not given so insufficient

Consider statement 2

.75(m+f)=students who applied for college=0.72m+ .80f
only one equation-- so not sufficient

Combining statement 1 and 2

two equations --two variables.

hence Answer is C
1437
1) Is x^y option 1 : y^2=x , then to check if x^y 2 the inequality remains the same y reverses --> no relevance
option 2 : y
so Answer is 5
------------------------------------------
2) Is 1/(a-b)
1) alet a-b = A then 1/A +A
so a-b should be definitely negative or definitely postive to get the answer.
Option 1 )a a-b Option 2) 1 a-b >1 or a-b
so Answer is 1
------------------------------------------
3) In the fraction x/y, where x and y are +v integers, what is the value of y?
1) the least common denominator of x/y and 1/3 is 6.
2) x=1

option 1 )Least common denominator of x/y and 1/3 is 6 so Y is a multiple of 6 like 6, 12, 18 etc ..
Option 2) x = 1 who cares :biggrin: this is not relevant at all..!!
so Answer is 5
rechecked-value of y could be 2 also.ans remains the same.
------------------------------------------
4)If x is a +ve integer and w is a -ve integer, what is the value of xw?

1) x^w= 1/2
2) w=-1

Option 1) x^w= 1/2 since w is negative. and the RHS is a 2^-x form,(2^-1)
X is a multiple of 2
2^w =1\2 w = -1
4^w =1\2 w = -1/2 ...
so on ....!!
but we know W is an integer , a negative integer so (x,w) can be only (2,-1)
so Answer is 1
------------------------------------------
5) Is x/m (m^2+n^2+k^2) = xm+yn+zk?

1) z/k = x/m
2) x/m = y/n

x*m^2+x*n^2+x*k^2) = x*m*m+y*m*n+z*m*k
x*n*n + x*k*k = y*m*n+z*m*k ? is the kostin..
option 1
z/k = x/m --> k*x =m*z
x*n*n + x*k*k = y*m*n+z*m*k -->x*n*n = y*m*n ? --> x*n =y*m ? so u cant answer from this
option 2
x/m = y/n -->m*y =x*n
x*n*n + x*k*k = y*m*n+z*m*k--> k*x =m*z ? so u cant answer from this
taking both u get x/m (m^2+n^2+k^2) = xm+yn+zk so
so Answer is 3
------------------------------------------
6)if k and n are integers is n divisible by 7?
1) n-3 =2k
2)2k+4 is divisible by 7.

option 1 : n =2k+3 --> no relevance
option 2 : 2k+4 is divisible by 7 no relevance to n
joining both n = 2k+4-1 --> 7p-1 so is not divisble by 7 hence
so Answer is 3



P.S: will add other answer in a while ..brb :lunch :biggrin:

I have tallied all the answers posted by Anil.

All are right.

I solved Q-2 by putting values for a and b.
1438

1) Is x^y
sorry for the typo puys .... :biggrin:

1439
1) Is x^y
sorry for the typo puys .... :biggrin:


Ans still remains at E ..

Coz we are interested to compare y^2y and y^(y^2) ...
Now, y could be -ve integers as well ...so it would depend whether y is -ve odd or -ve even ..
not decisive ..Ans E ...

Interestingly, you had posted a similar sum earlier where St 2 was y>2 ...then Ans would have been C ..
Here is the link : http://www.pagalguy.com/discussions/gmat-data-sufficiency-discussions-25020702

have not tried other sums yet ...will attempt after some time !
1440

Guys, here is a very simple DS, just want to confirm the answer..

If n is an integer and 100 n n?
(1) N/36 is an odd integer.
(2) N/45 is an even integer.

Another PS (sorry , i know that there is a different thread), i just want to make sure that my answers, which seem to be not matching to OA, are right..

At a certain company, each employee has a salary grade s that is at least 1 and at most 5. Each employee receives an hourly wage p, in dollars, determined by the formula p = 9.50 + 0.25(s 1). An employee with a salary grade of 5 receives how many more dollars per hour than an employee with a salary grade of 1?

A. $0.50
B. $1.00
C. $1.25
D. $1.50
E. $1.75

Cheers