GMAT Data Sufficiency Discussions

MBA GMAT
201
FIRST SET

1.
option 1 does not give us any clue.
in option 2, either both n,p>0 or both n,pusing both options together,
n>-1 and np>0, we know n is +ve..hence, p shud also be +ve..
hence, option C.

2.
using option1,
12u = 8y+12
hence, y = (12u-12)/8 = /8 in which case, no definite answer
using option2,
x=12z+12 = 12(1+z)...hence, we know FOR SURE the gcd is 12 in this case since 1+z is an integer...thus, answer is B.

3.
i dunno....even i wud hv marked E..

4.
the answer is B because there is only one combination that satisfies the price to be 130.... 23*2+21*4....try all other possible (23cents, 21cents) to see if u get a sum of 130 anywher (0,1), (0,2), (2,2), (4,4)....etc..


Q3 Eqution of any line is x/a + y/b = 1 slope of the line is -b/a .x intercept is a y intercept is b.
Now line l is x/a1+y/b1=1 slope -b1/a1
line k is x/a2+y/b2=1 slope is -b2/a2
product of slopes is (b1 *b2)/ (a1*a2) product of x intercepts is a1*a2 and product of y intercepts is b1*b2
With both statments we can say that product of slope is -ve.
so Answer is C
202
1.
AB=OC=OB=radius
in triangle BOC, let OBC=OCB=x degrees
hence, BOC=180-2x
in triangle ABO, let BAO=BOA=x degrees

using st.1,
COD=60,
hence, BOC+BOA=120 degrees
hence, 180-2x+x=120
hence, x=60...
st.1 is sufficient
using st.2,
BCO=40..hence, BAO=40
st.2 is also sufficient...
answer is D.

2.
i dunno man :(

3.
using st.1,
the only option that satisfies 530 miles is he drove the x miles in 7 hrs and remaining in 3 hrs...

hence, st.1 is sufficient

using st.2,
u do not know hw much time he took to cover the remaining distance..he cud take 6 hrs for the first part and 2 hrs for the remaining, or 17 hrs for the first and 13 for the second..so on..
so answer is A.


Q2
y>=0 what is value of x
option 1 does not lead to anything
option 2 mod(x-3) here y is 0 or positive number. so -y is 0 or -ve number
mod(x-3) cannot take -ve value. so if -y cannot be -ve number. so y=0 implies mod(x-3)=0 implies x=3
203
Hi Ajay & Sriram,
Thanks a ton for taking time out to answer the DS questions. If you get a few moments, please can you also try having a go at the set I have attached in Post#191 on Page 20 of this same thread?
http://www.pagalguy.com/discussions/gmat-data-sufficiency-discussions-25020702
Many thanks.
Regards,
-TTB
204
Hi Ajay,
Any reason why you have equated both sets of angles (OBC&OCB;) and (BAO&BOA;) with x? I can understand that OBC=OCB and BAO=BOA but why are all the 4 angles equal to each other, i.e: x? In other words, why is OCB = BAO which is what is implied if you treat both angles as x. Thanks.
Best Regards,
- TTB
1.
AB=OC=OB=radius
in triangle BOC, let OBC=OCB=x degrees
hence, BOC=180-2x
in triangle ABO, let BAO=BOA=x degrees

using st.1,
COD=60,
hence, BOC+BOA=120 degrees
hence, 180-2x+x=120
hence, x=60...
st.1 is sufficient
using st.2,
BCO=40..hence, BAO=40
st.2 is also sufficient...
answer is D.

2.
i dunno man :(

3.
using st.1,
the only option that satisfies 530 miles is he drove the x miles in 7 hrs and remaining in 3 hrs...

hence, st.1 is sufficient

using st.2,
u do not know hw much time he took to cover the remaining distance..he cud take 6 hrs for the first part and 2 hrs for the remaining, or 17 hrs for the first and 13 for the second..so on..
so answer is A.
205
Hi All,
Note: I had posted a similar question earlier. Please note however that the questions in this attachment are different from the earlier ones.
Attached are some of the questions from GMATPrep that I got wrong. The options marked with the bold black dot in the attachment are mine and are the wrong answers. The options marked by a square blue frame are correct as these are the correct answers marked by the software. However the software does not explain why a particular choice is correct and others are wrong. I will be very grateful if some of you can help justify why the correct choice is actually correct!
Many thanks.
- TheToastedBread

Q1 M managers,D directors T task force m1 is average salary of managers and d1 and t1 are for dircotrs and task force.
2 equations 1.m+d=t 2.mm1+dd1=tt1
Now opttions 1 d1=t1+15000 2 m1=t1-5000
substitute in eqation 2 mt1-5000m+dt1+15000d=t t1
rewrite (m+d)*t1 -5000m+15000d= (m+d)t1 ( because m+d=t)
you get m=3d
you can answer the question so Answer is C
Q2 form a series with (n,r) u get (5,0)/6,11/7,0/8,15/9,8/10,3/11,0/12,23/13,0
u can see the trend use both options u find remaineder is alwaus 0. so Answer is C
Q3. option 1 one country 41 A atleast 10 . assume other four 1,2,3,4. then A will be 24. if u change other four countries to 2,3,4,5 A will get diff answer. So using stamnet alone it cannot be answered. Stament B does not tell you anything. Using both stament as also you have choice of 9(others 4 6 7 and 10(others 457 or 11 (456 for A. So Answer is E
Q4. Using stament 1 xz is even. means atleast one of x or z is even. x is factor of z. if z is odd x ahs to be even. which is not possible becasue x is factor of z. so z must be even.
statment 2 if y is even z has to be even because y is factor of z. Answer is D
Q5 using staemnet1 x5=x4/2 and using stemnet 2 x5=x4/(x4+1).
using together x4=0 or 1 . if x4 is 0 all numbers in the sequence are 0.(is this considered as series ,all being 0's) i am not sure.
if x4=1 x1=8 . Shoul d the anwer be E if we consider all 0's as a series. or anwers is C
206

Hi Just to undestand scores
how many questions were correct ,how many were wrong. and what was quant and verbal and total score

207
Hi Just to undestand scores
how many questions were correct ,how many were wrong. and what was quant and verbal and total score

Sriram,
I have given the real GMAT twice now (coincidentally the second one just a few hours ago). So I know for a fact that getting number of questions right or wrong is not the only or the most important criteria. What matters a lot is how well you tackle the harder problems....eg: I would much rather attempt 10 hard questions and get 5 wrong rather than tackle 10 easy questions and get 2 wrong. I mean all this is inter-related no doubt because one may argue how can one get a chance to get to the difficult questions if one keeps on goofing the easier ones. But in any case dont get too much rattled by getting questions wrong. The harder ones are meant to induce mistakes. And it wont just happen with you. It will be the case with many fellow GMAT takers.
Regards,
- TTB
208

Hi!
I got the following questions wrong ...can someone explain the Correct answers?
------------------------------------------------------------ ---------------------------------
Q10:
If x2 + 3x + c = (x + a)(x + b) for all x, what is the value of c ?
(1) a = 1
(2) b = 2
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose C, but it is not correct ..?? Why?
------------------------------------------------------------ ---------------------------------
------------------------------------------------------------ --------------------------------- Q13:
Is the number of seconds required to travel d1 feet at r1 feet per second greater than the
number of seconds required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose C, but it is not correct ..?? Why?
my reasoning was let d2 = x and r2 = y, then t2 = x/y i.e. time taken to cover d2. Now 1 and 2 say d1 = x+30 and r1 = r2+30 i.e. t1 = (x+30)/(y+30) ..which is same as x/y...so bo the are required to say whether t1 > t2 or not? in this case t1 = t2
But the ans is D??
------------------------------------------------------------ ---------------------------------
Q16:
If n > 0, which is greater, 20 percent of n or 10 percent of the sum of n and 0.5 ?
(1) n (2) n > 0.01
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose D, but it is not correct ..?? Why?
------------------------------------------------------------ ---------------------------------

209
Hi!
I got the following questions wrong ...can someone explain the Correct answers?
------------------------------------------------------------ ---------------------------------
Q10:
If x2 + 3x + c = (x + a)(x + b) for all x, what is the value of c ?
(1) a = 1
(2) b = 2
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose C, but it is not correct ..?? Why?
------------------------------------------------------------ ---------------------------------
------------------------------------------------------------ --------------------------------- Q13:
Is the number of seconds required to travel d1 feet at r1 feet per second greater than the
number of seconds required to travel d2 feet at r2 feet per second?
(1) d1 is 30 greater than d2.
(2) r1 is 30 greater than r2.
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose C, but it is not correct ..?? Why?
my reasoning was let d2 = x and r2 = y, then t2 = x/y i.e. time taken to cover d2. Now 1 and 2 say d1 = x+30 and r1 = r2+30 i.e. t1 = (x+30)/(y+30) ..which is same as x/y...so bo the are required to say whether t1 > t2 or not? in this case t1 = t2
But the ans is D??
------------------------------------------------------------ ---------------------------------
Q16:
If n > 0, which is greater, 20 percent of n or 10 percent of the sum of n and 0.5 ?
(1) n (2) n > 0.01
A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is
sufficient.
D. EACH statement ALONE is sufficient.
E. Statements (1) and (2) TOGETHER are NOT sufficient.
Ans: I chose D, but it is not correct ..?? Why?
------------------------------------------------------------ ---------------------------------

Q.10.

we have
x2+3x+c = (x+a)(x+b)
= x2+(a+b)x+ab
hence,
3=a+b
c=ab
using st.1,
when a=1,
3=1+b
b=2
hence, c=2

using st.2,
when b=2,
3=a+2
a=1
hence,
c=2
thus, answer is D.


Q.13.
i guess the answer is C. they might have given the wrong answer because in my opinion, it is impossible to find whether d1/r1 is greater than d2/r2 without knowing relation between d1 and d2, r1 and r2...

Q.16.
the question can be simplified as :

.2n > .1(n+.5)

using st.1,
when n=.05,
lhs = .01
rhs = .055
lhsso st.1 is sufficient

using st.2,
when n=.02,
lhs = .004
rhs = .052
lhsrhs
so st.2 is nt sufficient
so answer is A.
210
Q.10.

we have
x2+3x+c = (x+a)(x+b)
= x2+(a+b)x+ab
hence,
3=a+b
c=ab
using st.1,
when a=1,
3=1+b
b=2
hence, c=2

using st.2,
when b=2,
3=a+2
a=1
hence,
c=2
thus, answer is D.


Q.13.
i guess the answer is C. they might have given the wrong answer because in my opinion, it is impossible to find whether d1/r1 is greater than d2/r2 without knowing relation between d1 and d2, r1 and r2...

Q.16.
the question can be simplified as :

.2n > .1(n+.5)

using st.1,
when n=.05,
lhs = .01
rhs = .055
lhsso st.1 is sufficient

using st.2,
when n=.02,
lhs = .004
rhs = .052
lhsrhs
so st.2 is nt sufficient
so answer is A.


Q13 : For me answer looks like E
d1/r1 and d1+30/r1+30 . we cannot conclude any thing from this which fraction is greater.
211

All of the furniture for sale at Als Discount Furniture is offered for less than the manufacturers suggested retail price (MSRP). Once a year, Als holds a clearance sale. If Jamie purchased a certain desk during the sale, did she get a discount of more than 50% of Als regular price for the desk?

(1) Als regular price for the desk is 60%, rounded to the nearest percent, of the MSRP of $2000.

(2) The sale price was $601 less than Als regular price for the desk.

Guy's.. what do you think is the answer ??

212
Q.10.

we have
x2+3x+c = (x+a)(x+b)
= x2+(a+b)x+ab
hence,
3=a+b
c=ab
using st.1,
when a=1,
3=1+b
b=2
hence, c=2

using st.2,
when b=2,
3=a+2
a=1
hence,
c=2
thus, answer is D.


Q.13.
i guess the answer is C. they might have given the wrong answer because in my opinion, it is impossible to find whether d1/r1 is greater than d2/r2 without knowing relation between d1 and d2, r1 and r2...

Q.16.
the question can be simplified as :

.2n > .1(n+.5)

using st.1,
when n=.05,
lhs = .01
rhs = .055
lhsso st.1 is sufficient

using st.2,
when n=.02,
lhs = .004
rhs = .052
lhsrhs
so st.2 is nt sufficient
so answer is A.




I think the answer for 10. is D, for 13 is D and for 16 its C.. can you let us know the correct answers given !!! Thanks..
213
All of the furniture for sale at Als Discount Furniture is offered for less than the manufacturers suggested retail price (MSRP). Once a year, Als holds a clearance sale. If Jamie purchased a certain desk during the sale, did she get a discount of more than 50% of Als regular price for the desk?

(1) Als regular price for the desk is 60%, rounded to the nearest percent, of the MSRP of $2000.

(2) The sale price was $601 less than Als regular price for the desk.

Guy's.. what do you think is the answer ??


Let MRSP is M . Sellinng price is S regular price is S. Now the question is Is S less than 50% of R
St 1 R=60% of M=60%of 2000= 1200. We have no idea on S. S could 1000,or 400. Nothing can be concluded
St2 S=R-601 =1200-601=599. Using st1 also.
We can say S=599 and R=1200. this is less than 50% of R. So answer is C
However theer is a twist. in st 1 R is roundede to 60%. Normally for G MAT purpose we shld ignire this and proceed as if it is 60%.
Since the anwer is close which can change the answer whether is is 60.2% or 59.8%. In that case answer is E.
214
Let MRSP is M . Sellinng price is S regular price is S. Now the question is Is S less than 50% of R
St 1 R=60% of M=60%of 2000= 1200. We have no idea on S. S could 1000,or 400. Nothing can be concluded
St2 S=R-601 =1200-601=599. Using st1 also.
We can say S=599 and R=1200. this is less than 50% of R. So answer is C
However theer is a twist. in st 1 R is roundede to 60%. Normally for G MAT purpose we shld ignire this and proceed as if it is 60%.
Since the anwer is close which can change the answer whether is is 60.2% or 59.8%. In that case answer is E.


Hi Sriram.. You are awesome !! you got it right.. Its one of the question from the manhattan test.. The answer was E.. but i marked as C.. so by what you in my GMAT test I should mark C.. right ? Thanks so much for answering..
215

I got this problem wrong in GMAT prep.

Q) Are x & y both positive ?

(1) 2x - 2y = 1
(2) x/y > 1

The correct answer is 'C'.

My answer is 'E' and explanation as follows.
when x = 3.5 and y = 3
then both conditions are satisfied. What if x = 0.45 and y = -0.05, even then both conditions are satisfied..

Can anyone explain why 'C' is the right answer

216
I got this problem wrong in GMAT prep.

Q) Are x & y both positive ?

(1) 2x - 2y = 1
(2) x/y > 1

The correct answer is 'C'.

My answer is 'E' and explanation as follows.
when x = 3.5 and y = 3
then both conditions are satisfied. What if x = 0.45 and y = -0.05, even then both conditions are satisfied..

Can anyone explain why 'C' is the right answer

u are right...answer is E..
all conditions are satisfied for both the solutions (-1,-1.5) and (5,4.5)
217
u are right...answer is E..
all conditions are satisfied for both the solutions (-1,-1.5) and (5,4.5)


Answer is C.
in both of your examples statement 2 is not satisfied.

2x-2y=1 implies x is greater than y
x/y is graeter than 1 means both x y are positiv or both negative.
if both are positive x is greater than y and if both are -ve x is smaller tha y
for ex to satisf st 2 5,4 or -5,-4 (-5 is smaller tha -4)
-5,-4 type pair can never satisfy st 1.
using both st only type 1 pair is possible . i.e both positive. so answer is C
218
Answer is C.
in both of your examples statement 2 is not satisfied.

2x-2y=1 implies x is greater than y
x/y is graeter than 1 means both x y are positiv or both negative.
if both are positive x is greater than y and if both are -ve x is smaller tha y
for ex to satisf st 2 5,4 or -5,-4 (-5 is smaller tha -4)
-5,-4 type pair can never satisfy st 1.
using both st only type 1 pair is possible . i.e both positive. so answer is C

dude, i hv written -5, -4.5...not -5,-4....since it is not mentioned that x and y MUST be integers...so the first condition is satisfied in all cases...
the answer, once again, has to be E.
219

Hi
2x-2y=1 with -5 , -4.5 2x-2y=-10-(-9) = -1 not satisfied.
Answer is C

220
Hi,

Here are a few DS questions I couldn't solve,


q1. A company enlisted P people to sell 200 knives each, and each salesperson then enlisted P more people to sell 200 knives each. If eveyone sold their 200 knives, what is the value of P?

1) the first P people sold 1/9 of all the knives sold?
2) 14,400 knives were sold in total.

q2. A group of theater owners made an arrangement with an acting company stating that the theater owners would get $5 for every ticket sold. How much did the theater owner earn from the ticket sales?

1) The total revenue was $700
2) If 30 more tickets had been sold, the theater owners would have recvd 30% more money from ticket sales.

q3. Set S consists of n numbers arranged in asc. order. A new set is created as follows: each element in S is increased by a value = that number's place in S. By how much does the mean of the new set > the mean of the original set?

1) set S has 10 elements
2) The sum of elements in the original set is 100.

q4. 3 segments are drawn from opposite corners of a hexagon to form 6 triangles. These segments all bisect each other at pt A. Are the triangles equilateral?

1) All 6 sides are the same length.
2) The 3 segments drawn between the opposite corners are the same length.

Can somebody please help me solve them?




Thanks,
Shipra