Data Sufficiency

hi there,
first time post here - but i notice that in your third question, you have not tried b=-1/2. if b=-1/2, then
2* -1/2 = -1;
a must be > -1; try a=-3/4. (Any value of a that is -1/2 < a < -1 works.)

-3/4 is greater than -1 but does not satisfy the a-b>0? question, because

-3/4 - (-1/2) = -3/4 + 1/2 = -3/4 + 2/4 = -1/4... which is <0. INSUF.

Statement 2 will always work, for both negative and positive values.

Answer B


I'm having a problem with your first question... if the product of the greatest and least value in the set is positive, then all products in the set must be positive.

Illustrated here:

Least ---------- Greatest 0 Least -------------- Greatest
... -4, -3, -2, -1 0 1, 2, 3, 4, 5, ...

There can't be any overlap through the zero horizon because then the product of the greatest and least would be negative. Thus this condition is sufficient to answer the yes/no question!

Am i missing something? Condition 2 is absolutely useless in my opinion.

Least ---------- Greatest 0 Least -------------- Greatest
... -5, -3, -1 0 1, 3, 5, ...



Hope there's an answer somewhere abouts.

I didn't understand how the answer to Q3 is B. b>a-3 can be satisfied for values of b less than a (e.g., 10>11-3) , but also for b greater than a (e.g., 100>11-3). So, how does b>a-3 imply that a-b>0?