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Possible cases:
x=5, y=6, z=9
x=5,y=7 z=8
x=5, y=7, z=9
x=4, y=7, z=9

4 total cases
4/(4*3*3)=1/9

C.

A more methodical method:
Look at set X and Y. The highest value it can take is 12 (7+5) so the lowest values of Z possible is 8.
That means x and y must sum to at least 11. If the sum is exactly 11, Z must be 9, otherwise if its greater it can be 8 or 9.

[quote="gmatophobia"] DS Question 1 - Mar 05 At a certain animal shelter, there are nine dogs available for adoption. If Susan chooses two dogs at random and p is the probability that Susan chooses two labradors, is p =3 makes condition on "p" true, hence we have check if number of Labradors =3 ?


STATEMENT 1:

we can form equation :
(x/9 * y/8) + (y/9 * x/8) > 1/2

2xy > 1/2 * 72
x(9-x) > 18

we can test some values of x starting from 9 to 0 descending we find only x=5 or x=4 satisfy the above condition. so x 1/10
y(y-1) > 7.2

trying you values of y, we get y=4 onwards all values satisfy the condition above. so y>=3 holds true as asked in question stem. so statement is also sufficient.


BOTH statement is sufficient ?
option D

DS Question 1 - Mar 07

If a = |b - 6| + |b + 2|, what is the value of a ?

(1) a is an integer greater than 7
(2) -2 < b < 6

Source: GMATNinja | Difficulty: Hard

PS Question 1 - Mar 07

If Z = 10^x + 10^y + 10^z , in which x, y, z are distinct positive integers. How many different values of Z are possible if Z < 10^9?

a) 24
b) 34
c) 56
d) 84
e) 120

Source: Others | Difficulty: Hard

From observation , we see if either of x,y,or z has be less than 9 , else z would be greater than 10^9. so max value of either of x,y,or z is 8. And since it is also given x,y,z are distinct +ve int. then we have max value x,y,z can be 8*7*6/3! ( as 10^1+10^2+10^3 is same as 10^3+10^2+10^1). Answer is C


B ??

B, since every value of a when -2 < b < 6 is 8.

Can we create something similar for whatsap? Many people dont longin daily to this chat, just a good for thought.

This can be rewritten as p^(m*n)=256.

16^2 = 256
4^4 = 256
2^8 = 256

16^2=4^2=2^8

Thus, m*n can be 2, 4, or 8.

Then possible values of n = 1, 2, 4, 8

So, possible values of n*n = 1, 4, 16, 64

B. I & III

We also don’t encourage use of 3rd party messengers. The reason we have this chat group is to collaborate and learn.


We don’t encourage use of 3rd party messengers. The reason we have this chat group is to collaborate and learn.

PS Question 1 - Mar 09

Fox jeans regularly sell for $15 a pair and Pony jeans regularly sell for $18 a pair. During a sale these regular unit prices are discounted at different rates so that a total of $9 is saved by purchasing 5 pairs of jeans: 3 pairs of Fox jeans and 2 pairs of Pony jeans. If the sum of the two discounts rates is 22 percent, what is the discount rate on Pony jeans?

A. 9%
B. 10%
C. 11%
D. 12%
E. 15%

Source: GMAT Paper Tests | Difficulty: Hard

DS Question 1 - Mar 09

Joe earned x dollars the first day he worked in December, where x is an integer. For each day after the first that he worked in December, Joe earned twice the amount he earned on the previous day. Did Joe earn less than $35 on the 4th day he worked in December?

(1) Joe earned more than $120 in total for the first five days he worked in December.
(2) Joe earned less than $148 on the 6th day he worked in December.

Source: Manhattan Prep | Difficulty: Hard

System of equations: let x be discount on Fox jeans and y discount on Pony jeans.


B.


A.

PS Question 1 - Mar 10

If (a + b) = 4, and ab = 7/4, what is the value of a^2 – b^2?

A. -12
B. 12
C. Either A or B
D. 16
E. None

Source: Official Guide | Difficulty: Medium

DS Question 1 - Mar 10

Is x > y^2?

(1) x > y + 5

(2) x^2 - y^2 = 0

Source: GMAT Club Tests | Difficulty: Hard

a^2-b^2 = (a+b)(a-b) , we already know a+b , so for (a-b)^2 can be written as (a+b)^2-4ab , hence a-b = 3 or -3, hence a^2-b^2 = 4*3 i.e 12 or 4*-3 =-12

PS Question 1 - Mar 11

The ratio of a two digit number to a number formed by reversing its digits is 4:7. Which of the following is the sum of all the numbers of all such pairs?

A. 110
B. 200
C. 330
D. 88
E. 770

Source: Others | Difficulty: Medium

DS Question 1 - Mar 11

W, X, Y and Z are four different positive integers. When X is divided by Y, the quotient is Z and the remainder is W.
What is the value of Z?

1) W = X – 4
2) W + Z = 4

Source: GMATPrepNow | Difficulty: Hard

(10a+b) / (10b+a) = 4:7
=> 2a=b
or b is even, for a number "ab" and "a" is half of "b"
such numbers are = 12,24,36,48
and "ba" to form pair = 21,42,63,84

sum of above all number pairs = 330 option C

X=YZ+W
find Z
statement1:
W=X-4
so, YZ=4 since X,Y,Z,W are different positive int;
Y=4 OR 1, Y is used to divide the number X, if its 1 there will be no remainder
but W is a positive number, so Y IS NOT hence Y = 4 and Z=1
so sufficient

statement2:
YZ-Z+4=X
still too many variables to account for. not conclusive
(W,Z) = (1,3) , (2,2) SO ON

Option A ?

C , (10a+b)/(10b+a)=4/7 , we get a=2b , now putting values in b such that 10a+b and 10b+a remains 2 digit numbers , we get 21,42,63,84 (10a+b) and 12,24,36,48 (10b+a) , adding them all we get 330.


A??