GMAT Data Sufficiency Discussions

A person bought an article at 15% discount and sold it for Rs 1600. What is the % profit?
(I) The marked price is 1500
(II) By selling the article at Rs 153 more, he would get 12% more



IMO D.

my expn:

take 1)clearly we can calc the profit.

1500*0.85=1275 % profit = 1600-1275/1275 * 100

take 2) here 153 is 12% so 100% is 1275 so we know the cost price and we can calc the % profit.

So D.
Solve this:

What is the proportion of women in Austria?
(I) Number of men in Austria is 5% more than the number of women
(II) Austria's population is 5% more than that of one of its neighboring countries, where women are 52% of the population.



IMO A

take1) W/M+W = W/2.05W so 1) Alone is suff.

take 2) onlly percentages present no information on the actual demographics.

So A is suff.
The roots of a quadratic equatin ax^2+bx+c=0 are integers and
a+b+c>0 and a>0. Are both the roots of the equation positive?

(1) Sum of the roots is positive.
(2) Product of the roots is positive


IMO C.

Take 1) sum of roots is b/a. from here we dont get any information on c/a

Take 2) c/a is +ve this means c is also +ve. but no information on b.
take both 1) and 2) we have a>0 c>0 and b
So both the roots are +ve,



any alternative explanation puys?

Puys,
a long list of problems.. But the pain is I donthave the OA. I found these questions unanswered in earlier posts.


2. Is the five digited number ABCDE divisible by 13?
1. The number CD is divisible by 13.
2. 10A+B+4C+3D-E is divisible by 13.


Very interesting ...I am not sure if divisibility rules of 13 are expected on GMAT..

Nevertheless, couple of things to learn from this sum :
Div rules of 13 ;

a) Delete the last digit from the given number. Then subtract nine times the deleted digit from the remaining number. If what is left is divisible by 13, then so is the original number.

b) To find out, if a number is divisible by 13, take the last digit, Multiply it with 4, and add it to the rest of the number.

If you get an answer divisible by 13 (including zero), then the original number is divisible by 13.

If you don't know the new number's divisibility, you can apply the rule again.

Was aware of the first one ...and to generalize, modualr technique is used ...just learnt abt it ...can google to get the details ..

St 1 : It does not depend on any 2 specific digits ...not suff..

St 2 : generalised form of modular algebra ...Suff

IMO, Ans B
Puys,
a long list of problems.. But the pain is I donthave the OA. I found these questions unanswered in earlier posts.

4. In triangle ABC angle A is the greatest angle. D is the foot of the
perpendicular dropped on to BC from A. Is triangle ABC
right-angled?
1. AD^2= BD x DC.
2. AD/DC


If triangle ABC is rt angled at A, and AD is perpendicular to hypotenuse, then triangle ACD and BAD is similar
So AD^2 = CD *BD

Reverse is true as well ...given this ratio , triangle is a rt angled triangle at A..

St 1 : ratio given, hence, rt angled at A ...suff

St 2: unequal ratios, hence not a rt angled at A ..suff

IMO ...Ans D ..
Puys,
a long list of problems.. But the pain is I donthave the OA. I found these questions unanswered in earlier posts.

6.If x and y are positive integers such that x= 8y +12 ,what is the GCD of x and y?
a) x=12u , where u is an integer
b) y=12z , where z is an integer

My take on

Q6.Both statements are nt suff and additional info is needed to ans the q


I guess Ans should be B

x=8y+12

St 1 : tells us nothing abt y ...not suff

St 2 : y=12z
Hence, x = 8*12*z + 12 = 12(8z+1)
And y = 12z

Hence, GCD has to be 12 since there can be no common factor between z and (8z+1) except 1

Hence, IMO ans B ...any better soln puys
Puys,


6.If x and y are positive integers such that x= 8y +12 ,what is the GCD of x and y?
a) x=12u , where u is an integer
b) y=12z , where z is an integer


statement1.8y=12u-12=12(u-1)
y=12(u-1)/8=3(u-1)/2
to make y an integer ,value of u will be 3,5,7,9.....giving different values of x,y.not suffecient.
statement2.x=12(z+1) =>x and y both are multiples of 12.for every value of Z will give even and odd values of x/y.
so B
Is x + y > 0 ?
(I) x - y > 1
(II) x/y + 1 > 0


(x-y)(x+y)>1. Not suff
x+1>o. Not suff.

Hence E(option E)

Dear bradcapo1 sir,

You can thank any post using thank button provided in every post, its not necessary to post thank separately.

Regards,



Thanks everyone for your support, you're the best!!



taux pret auto - taux pret auto differe selon la rise en compte ... calculent automatiquement le taux pour un prt automobile donne.

If N is a positive integer, what is the last digit of the result for

1! + 2! + ....+ N! ?

1) N is divisible by 4

2) (N2 + 1 ) / 5 is an odd integer

Puys attack this one.. OA later

If N is a positive integer, what is the last digit of the result for

1! + 2! + ....+ N! ?

1) N is divisible by 4

2) (N2 + 1 ) / 5 is an odd integer

Puys attack this one.. OA later



If N =1 then last digit would be 1
If N =2 then last digit would be (1+2 )= 3
If N =3 then last digit would be (1+2+6) =9
If N =4 then last digit would be (1+2+6+24) =3
If N >4 then last digit would be (1+2+6++4+0) =3

Option 1) N is divisible by 4 so N = 4,8,12,16 etc...last digit of all the numbers is 3 ..so option 1alone is suff
Option 2) (N^2 +1)/5 is an odd integer ...
N =1 , (N^2 +1)/5 = fraction
N=2 , (N^2 +1)/5 =1
N=3 , (N^2 +1)/5 =2 N=4 , (N^2 +1)/5 = fraction

So the number N can be 2 or any number greater than 4...but if v see above for N=2 , N >4 the last digit is 3...

So v can say they Option 2 alone is suff...!!

Please let me know if i am on the right track of solving πŸ˜‰

My Ans is D ...Whats OA ?

Both the statements are independantly suff to find the "last digit of the result for 1! + 2! + ....+ N! ?"

If N is a positive integer, what is the last digit of the result for

1! + 2! + ....+ N! ?

1) N is divisible by 4

2) (N2 + 1 ) / 5 is an odd integer

Puys attack this one.. OA later



OA is D indeed.

One more

Is xy>0?

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

One more

Is xy>0?

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



I think C.
Sketch the two and the common region comes out to lie in the Ist quad. Hence xy>0.

Either 1 or2 doesn't give an exclusive answer.

Whats the OA?

When u combine both the statements u can get an answer

One more

Is xy>0?

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



=========================================================
Hi,


My take is for E.

Regards,
:drinking:
==========================================================
If N is a positive integer, what is the last digit of the result for

1! + 2! + ....+ N! ?

1) N is divisible by 4

2) (N2 + 1 ) / 5 is an odd integer

Puys attack this one.. OA later



Hi,

I`ll go for Option-D.

cheers !
:drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking::drinking:
One more

Is xy>0?

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



OA is C.

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