GMAT Math : GMAT Quantitative Reasoning

Study concepts, example questions & explanations for GMAT Math

varsity tutors app store varsity tutors android store

Example Questions

Example Question #2 : Dsq: Calculating X Or Y Intercept

Give the -intercept of the graph of the function 

Statement 1: 

Statement 2: 

Possible Answers:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Correct answer:

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Explanation:

To find the -intercept of , evaluate :

Knowing both  and  is necessary and sufficient.

Example Question #2 : X And Y Intercept

Give the -intercept of the graph of the function 

Statement 1: 

Statement 2: 

Possible Answers:

BOTH statements TOGETHER are insufficient to answer the question.

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Correct answer:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

Explanation:

To find the -intercept of , evaluate :

Knowing  is necessary and sufficient; the value of  is irrelevant.

Example Question #6 : X And Y Intercept

A line on the coordinate plane is neither horizontal nor vertical. Give its -intercept.

Statement 1: The line passes through .

Statement 2: The line passes through .

Possible Answers:

BOTH statements TOGETHER are insufficient to answer the question. 

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Correct answer:

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Explanation:

Two points are necessary and sufficient to define a line. Therefore, neither statement alone is sufficient to determine the line, but both are sufficient. Once the line is defined, the -intercept - the point at which the line intersects the -axis - can be determined.

Example Question #1 : X And Y Intercept

 and  are two distinct nonvertical lines on the coordinate plane.

True or false:  and  have the same -intercept.

Statement 1:  and  intersect at .

Statement 2:   and  are perpendicular.

Possible Answers:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

Correct answer:

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

Explanation:

The question is equivalent to asking whether the lines intersect at a point on the -axis. 

Assume Statement 1 alone. Since  and  are distinct lines, , their common -intercept, is their sole point of intersection. They cannot intersect at a second point, so they cannot have the same -intercept.

Assume Statement 2 alone. Perpendicular lines are lines that meet at right angles; the question of their point of intersection is not answered by this statement.

Example Question #7 : X And Y Intercept

A function  is graphed on the coordinate plane. Give the -intercept of the graph.

Statement 1: 

Statement 2:  

Possible Answers:

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Correct answer:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

Explanation:

The -intercept of the graph of  is the point at which it intersects the -axis. Since this point has -coordinate 0, the -coordinate is . Statement 1 does not give us this value, but Statement 2 does.

Example Question #8 : X And Y Intercept

 and  are two distinct nonvertical lines on the coordinate plane.

True or false:  and  have the same -intercept.

Statement 1:  and  have different -intercepts.

Statement 2:   and  both have slope .

Possible Answers:

EITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

Correct answer:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

Explanation:

The question is equivalent to asking whether the lines intersect at a point on the -axis. 

Statement 1 only establishes that the lines pass through different points on the -axis; no clues are given about any of their other points.

Statement 2 establishes that the lines have the same slope, and, subsequently, are parallel - that is, they do not intersect at all. Therefore, they cannot have the same -intercept.

Example Question #1 : X And Y Intercept

Continuous function  has the set of all real numbers as its domain.

How many -intercepts does the graph   have?

Statement 1: If , then .

Statement 2: .

Possible Answers:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Correct answer:

BOTH statements TOGETHER are insufficient to answer the question. 

Explanation:

The two statements together prvide insufficient information.

Assume both statements are true. By Statement 1,  is a constantly increasing function, so it can intersect the -axis at most one time.

Now examine these two cases.

 

Case 1:

.

Also, if , then , so .

Since , the function has exactly one -intercept.

 

Case 2: 

Also, if , then , so .

However, 2 raised to any power must be positive, so there is no value  for which . The function has no -intercepts. 

Example Question #11 : Dsq: Calculating X Or Y Intercept

Mandy's teacher challenged her to write numbers in the circle, the square, and the triangle in the pattern below in order to make an equation whose graph has -intercept  and -intercept .

Did Mandy succeed?

Statement 1: Mandy wrote a 5 in the triangle. 

Statement 2: The number Mandy wrote in the square was five times the number she wrote in the circle.

Possible Answers:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

EITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Correct answer:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

Explanation:

Let  stand for the values Mandy wrote in the square, the circle, and the triangle, respectively. The equation becomes

.

From Statement 1 alone, we know that Mandy wrote a 5 in the triangle, but we do not know any of the others. The question of Mandy's success is unresolved.

Now assume Statement 2 alone is known. Then 

.

The equation can be rewritten as

and it can be rewritten in slope-intercept form as 

Mandy wrote an equation whose line has slope .

However, the slope of a line through  and  is

.

Statement 2 alone is sufficient to establish that Mandy did not succeed.

Example Question #12 : X And Y Intercept

A line on the coordinate plane is neither horizontal nor vertical. Give its -intercept.

Statement 1: The line has slope .

Statement 1: The line passes through the origin.

Possible Answers:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are insufficient to answer the question. 

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Correct answer:

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

Explanation:

Statement 1 provides insufficient information, since the slope of the line alone is not enough from which to deduce the -intercept. Statement 2 alone tells us that the line passes through the point ; since this is on the -axis, this is the -intercept.

Example Question #13 : X And Y Intercept

Stanley's teacher challenged him to write numbers in the circle, the square, and the triangle in the pattern below in order to make an equation whose graph has -intercept .

Did Stanley succeed?

Statement 1: Stanley wrote a 4 in the square.

Statement 2: Stanley wrote a 16 in the triangle. 

Possible Answers:

BOTH statements TOGETHER are insufficient to answer the question. 

Statement 2 ALONE is sufficient to answer the question, but Statement 1 ALONE is NOT sufficient to answer the question.

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is NOT sufficient to answer the question.

EITHER statement ALONE is sufficient to answer the question.

Correct answer:

BOTH statements TOGETHER are sufficient to answer the question, but NEITHER statement ALONE is sufficient to answer the question.

Explanation:

Let  stand for the values Stanley wrote in the square, the circle, and the triangle, respectively. The equation becomes

.

To find the -coordinate of the -intercept, set  and solve for :

It is therefore necessary and sufficient to know the values of  and  - the values Ralph wrote in the square and the triangle - in order to determine the -intercept of Ralph's equation. Each statement alone give only one of those numbers; the two together give both.

Tired of practice problems?

Try live online GMAT prep today.

1-on-1 Tutoring
Live Online Class
1-on-1 + Class
Learning Tools by Varsity Tutors