GMAT Data Sufficiency Discussions

Plz post the explanations as well.

1.If the operation * is one of the four Arithmatic operation addition,Subtraction,Multiplication and division.Is (6*2)*4=6*(2*4)
A)3*2>3
B)3*1=3

2..Is z equal to Median of the three positive integers x,yand z.
A)x


1)answer is A as
A)3*2>3=>*=addition or *=multiplication and both are associative=>(6*2)*4=6*(2*4)

B)3*1=3=>*=multiplication or *=division
(6*2)*4=6*(2*4) is same for multiplication but different for division

2)answer is B as
the middle number with x,y,z written in ascending order gives median. now if x=x,z,z is the ascending order . if y=zz,z,x is ascending order hence z is median in both cases.
Hey all,

got 1 more doubt please.

If a certain grove consists of 36 pecan trees, what was the yield per tree last year?
*(1) The yield per tree for the 18 trees in the northern half of the grove was 60 kilograms last year.
*(2) The yield per tree for the 18 trees in the eastern half of the grove was 55 kilograms last year
Thanks and Regards,
Maunang

well the answer is E for two simple reasons :

1. we do not know the no. of trees that were there last year...

2. we have no idea about the yield in the western and southern half of the field...
heyy all,

have another doubt in a DS question.
This is from one of kapla practice tests.

The queston is some tig like this :

Question : A set consists of 11 consecutive integers. Which is the greatest integer?

1)If x is the smallest integer, then

2)If x is the smallest integer, then


Answer given is A.

But what does "if x is the smallest integer" mean here. What if x is not the smallest integer? A little confused and here and i marked E.

Can some one please elucidiate this question and answer.

Thanks and Regards,
Maunang

dude...its plain simple and easy...since u can get a unique value of x frm the first equation and since x is the smallest integer and since there are 11 consecutive nos., x+10 will be the largest integer...so the answer is A
as regards the 'if..' thing, they are asking u to assume that x is the smallest integer and then try to see if the question can be answered here..dont try to rack ur brains too much man!! it can get confusing if u try to delve into 'deeper' meanings of each sentence...gmat is much simpler than CAT...the language of questions too....
well the answer is E for two simple reasons :

1. we do not know the no. of trees that were there last year...

2. we have no idea about the yield in the western and southern half of the field...


Shit man i did not realise they asked for the last year.
Thanks:)

Regards,
Maunang
Any pointers, how to go about solving inequalities questions. Invariably I always get them wrong. Like this 1:

Q1) What is the value of x? (1) x = -x
(2) x2 = 4

Ans : B

dude...this problem's pretty easy....see, u obviously wont get a value using st.A...but thru st.B, u can conclude tht x = +2 or -2....however, they are asking u the absolute value of x...in this case, its 2...so u get a unique answer...
Hi,
Cud someone1 provide an explaination to the above question?

considering option 1:

since the greatest common factor of both the nos. is 2, it means tht the nos. cud be 4&6, 4&10, 6&10 etc...divide any two such nos. and the remainder will always be greater than 1..infact, i think in most cases it is exactly 2...hence, this statement is sufficient to answer the question

option 2 :

the LCM is 30...so the nos. cud be 6&10, 3&10, 15&30, 3&30, 6&30 etc... and try dividing any of these combinations, the remainder will always be greater than 1....this statement is also sufficient on its own to answer the question.
so the answer is C

$10,000 is deposited in a certain account that pays r percent annual interest compounded annually, the amount D(t), in dollars, that the deposit will grow to in t years in given by D(t)=10,000(1+(r/100))t What amount will the deposit grow to in 3 years?

(1) D(t) = 11,000
(2) r=10


according to me. 'r' is needed and thus the answer is B. wht say?:neutral:

In a demographic study, the population and total income of a certain region were estimated from other data, and both estimates had lower and upper limits. At the time of the estimates, was the per capita income for the region greater than $16,500?
(1) The lower limit for the estimate of the population was 330,000 people.
(2) The lower limit for the estimate of the total income was $5,500,000,000.

pls solve.


Hi friends,

See attached an official GMATPrep question. The correct answer is Choice D. However I am not able to work my way to the correct justification. Any help will be most gratefully received.
Many thanks.
- TheToastedBread
In a demographic study, the population and total income of a certain region were estimated from other data, and both estimates had lower and upper limits. At the time of the estimates, was the per capita income for the region greater than $16,500?
(1) The lower limit for the estimate of the population was 330,000 people.
(2) The lower limit for the estimate of the total income was $5,500,000,000.

pls solve.

see, both the options are insufficient to solve the question when used individually...but when used together, we knw that the lower limit of population was 5,500,000,000 and the lower limit of income was 330,000...per capita income is calculated as income/population...so this comes out to be 16,666..this means that the per capita is atleast 16,666 since this is the lower limit..hence we can conclude that the per capita income is greater than 16,500....answer is C
Hi friends,

See attached an official GMATPrep question. The correct answer is Choice D. However I am not able to work my way to the correct justification. Any help will be most gratefully received.
Many thanks.
- TheToastedBread

see, the equation can be rewritten as :
x
1 - when y>0, take any value of y>0...2,3,4....the corresponding values of x will be x
2 - we are given that x

y-20 = 0...y = 20....x = -40
-8y-20 = 0...y = -20/8....x = -60/8

hence, the value of x will always be less than 0...
thus statement 2 is also sufficient to answer on its own

1 question...

What are the values of X and Y?

(1) X^2 + Y^2 = 0
(2) X^2 - Y^2 = 0

1 question...

What are the values of X and Y?

(1) X^2 + Y^2 = 0
(2) X^2 - Y^2 = 0

acc. to me, the answer shud be 'A' if both X and Y are real numbers...cuz if thats the case, then frm eq.1 we get X^2 = -Y^2 which is possible only if either of them is an imaginary number...but since both of them are real numbers, the only value that satisfies this condition is ZERO. eq.2 does not giv a unique value..
1 question...

What are the values of X and Y?

(1) X^2 + Y^2 = 0
(2) X^2 - Y^2 = 0


answer is A as x^2+y^2=0 =>x=y=0
ratheen11 Says
answer is A as x^2+y^2=0 =>x=y=0


the answer given is A...but I've following doubt.
how can we say that x and y are real numbers?If they are imaginary...
x^2 = - y^2..which will give different answer? shouldn't the answer be C.
the answer given is A...but I've following doubt.
how can we say that x and y are real numbers?If they are imaginary...
x^2 = - y^2..which will give different answer? shouldn't the answer be C.

In the instructions before the test GMAT specifies that all numbers are real.
Therefore if x^2-y^2=0 => x=y or x=-y =>{x,y}={0,0},{1,1},{1,-1}, etc. i.e no single value. =>only 1 gives the exact answer.=>A

If n=p/q(p and q are nonzero integers),is n an integer?

1) n^2 is an integer
2) (2n+2)/4 is an integer

If n=p/q(p and q are nonzero integers),is n an integer?

1) n^2 is an integer
2) (2n+2)/4 is an integer

i gues the answer is E...because, n = p/q where both p and q are non zero INTEGERS.. hence, n can be either 3/2 or 4/2.. obviously, st.2 is not sufficient to answer because n can be 3/2
If n=p/q(p and q are nonzero integers),is n an integer?

1) n^2 is an integer
2) (2n+2)/4 is an integer




Hi!

p & q both are integers
n^2 is integer
=> p^2/q^2 is integer
Hence p/q shud be integer
IMO, 1) satisfies the requirement
2) Does not satisfy the requirement

Hence answer shud be A)
If n=p/q(p and q are nonzero integers),is n an integer?

1) n^2 is an integer
2) (2n+2)/4 is an integer


1) n^2=I =>n=+SQRT(I) and -SQRT(I) . Now if SQRT(I) is either irrational or integer
since SQRT(I) = p/q =>not an irrational no. =>SQRT(I) is an integer =>n is an integer.

2)(n+1)/2 =I =>n=2I-1 =>n is an integer

Therefore Ans is D .Do let me know if I am right.