What does "must be ture" mean in the math context?

[aimhier]

I have two questions concerning the same topic:

(1)Given that a < 5, and b - a = 0, which of the following must be true about b?

A) b = 5
B) b ≥ 5
C) b ≤ 5
D) b < 4
E) b > 5

The answer is C; the rationale given is from http://www.beatthegmat.com/mba/2013/04/ ... perts-miss

why can b=5?


(2) If 20x = 49y, which of the following must be true?

I. x > y
II. x^2 > y^2
III. x/7 is an integer

A) I only
B) II only
C) III only
D) I and III
E) I, II, and III
the answer is C, my quesition is: what if both x&y are 0?

[jnelson0612]

I have two questions concerning the same topic:

(1)Given that a < 5, and b - a = 0, which of the following must be true about b?

A) b = 5
B) b ≥ 5
C) b ≤ 5
D) b < 4
E) b > 5

The answer is C; the rationale given is from http://www.beatthegmat.com/mba/2013/04/ ... perts-miss

why can b=5?


(2) If 20x = 49y, which of the following must be true?

I. x > y
II. x^2 > y^2
III. x/7 is an integer

A) I only
B) II only
C) III only
D) I and III
E) I, II, and III
the answer is C, my quesition is: what if both x&y are 0?

Hi,
For that first question, do you know what the original source is? Is it just something that someone made up for Beat the GMAT or is it from somewhere else? That knowledge will help me help you.

For the second one, if x=0, then x/7 is 0/7 which is 0. Zero is an integer so that would be okay.