number properties

arorag wrote:If x and y are positive, is 3x > 7y?
(1) x > y + 4
(2) -5x < -14y


Ans D????
IMO B

i go with D as well...

statement 1,

take the minimum value of X and y

X should be 6 and y 1 ( i am taking integers for convenience sake... the Questions doesnt say anything abt integers)

6> 1+4

3X>7y

3.6 >7.1 yes.... sufficient.

statement 2.
-5x < -14y

X= 3 y = 1
-15< -14

3*3 > 7*1 hence sufficient..

hence D.

hope that helps..

How abt y= 5 then y mabe 10
30> 63?????

arorag wrote:How abt y= 5 then y mabe 10
30> 63?????

i dint understand ur question ...

lets say y=5, then y+ 4= 9
now to satisfy stat.I x> 9
lets assume x= 10
Now
is 3x>7y???

arorag wrote:lets say y=5, then y+ 4= 9
now to satisfy stat.I x> 9
lets assume x= 10
Now
is 3x>7y???

ur right ... ru sure abt the OA? whats the source...

Let us reprase the question
IS 3x > 7y

x > 2.33y ?

This is a YES/NO question

Now let us check option 1:
x > y + 4 : Insufficient as
it does not give us conclusive answer

Even if we try to plug numbers
when y = 1 , x = 5 , means x is greater than 2.33y YES
BUT when y = 4 , x = 8 , x is less than 2.33y NO

This means we cant get definite answer

check option 2:
-5x < -14y
x > 14/5y
x> 2.8 y

means x is greater than 2.333y
=> YES ( it can answer the question )
SUFFICIENT


ANSWER therefore is B: option 2 alone

IMO: B