GMAT Problem Solving Discussions

I am not sure of the answer choice I would have marked.. but I can try..

Centered @ (0, 0)... and also A > B > 0
this means both A and B are positive and both lie inside the Quad I

so we dont care for the remaining Quads and we get the probability of both being positive as (1/4).

prob of A > B, this I am not sure how to figure out..

very frankly.. if I would have not known the correct answer from you, I would have suggested option B only, since A > B > 0 can be percieved as a way of saying that both A and B are greater than 0.

Lemme know if you get the means to figure out the correct answer..

You just draw the line x=y.And for all the points below the line x=y ,x>y.These occupies half of the I quardrant.
You can observe that only in the first quadrant the coordinates are positive ie. A>0 and B>0 as given in the condition.
Also there are total 8 patitions in which we can divide the xy plane which i cant draw here to explain.
Also A>B in I quadrant below line x=y.
Hence probability is 1/8 obviously.I think u have not checked for the condition th is both coordiantes should be positive.


one qq... hows do you divide a XY plane into 8 parts..??.. I knew of only 4 quads and I would really appreciate if you could explain me this 8 parts thing.. ;)

I dont recall all the co-ordinate geometry fundas, but as far as I remember, it used to have only 4 quads in xy plane.. plz share your thoughts..
shakti_1982 Says
You just draw the line x=y.And for all the points below the line x=y ,x>y.These occupies half of the I quardrant.


Let the radius be 2units... X can be 2units and Y can be 0.00000000001unit, or vice versa...

How did you reach the conclusion highlighted above conclusion..??..
Let the radius be 2units... X can be 2units and Y can be 0.00000000001unit, or vice versa...

How did you reach the conclusion highlighted above conclusion..??..


See varun. take a graph paper and draw lines two lines x=y passing through origin these two lines you will observe will divivde the x,y plane in 8 equal area sections.
Now by prniciple of geometry the x coordinate is greater than y in half of I quadrant only for x>y>0.
I hope you understood.

Yeah.. got ya point about x > y > 0, iff in Quad I.. In total agreement with you. ;)

I had trouble comprehending your thing about x=y... got that now.. cool!! thanks man!!

The four sides of a parallelogram all have the same length. If the angle between two of the sides is 60 degrees,
what is the ratio of the shorter diagonal to the longer diagonal?
A. 1 : 3
B. 1 : 3
C. 3 : 2
D. 3 : 4
E. 2 : 3

Any idea how to solve this?

The four sides of a parallelogram all have the same length. If the angle between two of the sides is 60 degrees,
what is the ratio of the shorter diagonal to the longer diagonal?
A. 1 : 3
B. 1 : 3
C. 3 : 2
D. 3 : 4
E. 2 : 3

Any idea how to solve this?


Sol: It is a rhombus.So if all sides be equal to a.
Now,cos 60=1/2=2a^2-l1^2/2*a^2=>a^2=2a^2-l1^2=>a^2=l1^2...i

And cos 120=-1/2=2a^2-l1^2/2*a^2=>-a^2=2a^2-l1^2=>3a^2=l2^2...ii
i and ii=>l1^2/l2^2=1/3=>l1/l2=1/3
Sol: It is a rhombus.So if all sides be equal to a.
Now,cos 60=1/2=2a^2-l1^2/2*a^2=>a^2=2a^2-l1^2=>a^2=l1^2...i

And cos 120=-1/2=2a^2-l1^2/2*a^2=>-a^2=2a^2-l1^2=>3a^2=l2^2...ii
i and ii=>l1^2/l2^2=1/3=>l1/l2=1/3



here if we assume side=10

then longer side=tan120=tan60=x/10

so longer side=1.73*10=17.3

for shorter side inner triangle became ,equilateral triangle so shorter dia=10

so ans is 10:17.3=1:sqrt 3
here if we assume side=10

then longer side=tan120=tan60=x/10

so longer side=1.73*10=17.3

for shorter side inner triangle became ,equilateral triangle so shorter dia=10

so ans is 10:17.3=1:sqrt 3


Take any triangle As diagnols bisects at 90 degrees.
So tan 30=d1/d2=>d1/d2=1/3.

Can someone provide me the table of values for sin, cos and tan?

ramviswa Says
Can someone provide me the table of values for sin, cos and tan?

Trigonometry ratios, values, Trignometry table of sin, cos, tan, cosec, sec, cot
Trig Triangle Formula Tables
ramviswa Says
Can someone provide me the table of values for sin, cos and tan?



0 30 45 60 90

Sin 0 0.5 1/ (2)^0.5 ((3)^1/2)/2 1

Cos 1 ((3)^1/2)/2 1/ (2)^0.5 0.5 0

Tan 0 1/((3)^1/2) 1 (3)^1/2 n.d.
1. 10*8*6 = 240.

2. 5! - (3!x2x2) = 96
3.
a)Total number of possibilities - (number of possibilities of couples sitting together).

Ans: 9! - (6!x2x2x2) = 6!x496

b) I dunno how to solve for this one.

c) 6!x2x2x2 = 8x6!



Let me know if you need explanation.


Can you please explain the answer to first question?
The four sides of a parallelogram all have the same length. If the angle between two of the sides is 60 degrees,
what is the ratio of the shorter diagonal to the longer diagonal?
A. 1 : 3
B. 1 : 3
C. 3 : 2
D. 3 : 4
E. 2 : 3

Any idea how to solve this?


let say diagonals are d1,d2
Lets say one of the daigonal facing 60 degree angle is d1.this forms equilateral triangle so d1=4.
Total area of parralelegram=2*sqrt(3)*4*4/4=1/2*d1*d2
d2=sqrt(3)
d1:d2=1:sqrt(3)
1. 10*8*6 = 240.

2. 5! - (3!x2x2) = 96
3.
a)Total number of possibilities - (number of possibilities of couples sitting together).

Ans: 9! - (6!x2x2x2) = 6!x496

b) I dunno how to solve for this one.

c) 6!x2x2x2 = 8x6!



Let me know if you need explanation.

For problem 3(b)

P(E)=(8!.2!)/9!=2/9

the triangle formed by the intersection of will have angles as 30 deg, 60 deg and 90 deg.
So d1/2 = x cos 60 = x/2, d1 = x
d2/2 = x sin 60 = xsqrt(3)/2, d2 = x sqrt(3)

so d1/d2 = 1: sqrt(3)

is trignometry in syllbs of gmat?

Rohit,
GMAT covers all the basics in Math including Trigno, a little bit of everything is covered, nothing advanced.

i keep visiting this thread and share some of the good questions from my old GMAT notes. here is another one.

5 chairs, 2 couple and one single person.
What is the probability that no couple sit together.

i keep visiting this thread and share some of the good questions from my old GMAT notes. here is another one.

5 chairs, 2 couple and one single person.
What is the probability that no couple sit together.


The Total ways to arrange 5 people=!5
case1. When first couple is sitting together=!4*!2
cas2.When second couple sitting together=!4*!2
case3.when both couples sitting together=!3*!2*!2
so the number of ways when couples are sitting together=case1+case2-case3
=96-24=72
so probability=72/120=3/5