GMAT Math : GMAT Quantitative Reasoning

Study concepts, example questions & explanations for GMAT Math

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Example Questions

Example Question #3 : Dsq: Calculating Mode

What is the value of  in the list above?

(1)

(2) The mode of the numbers in the list is .

Possible Answers:

Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient.

Statements (1) and (2) TOGETHER are not sufficient.

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

 

Each Statement ALONE is sufficient.

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Correct answer:

Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient.

Explanation:

The mode is the value that appears most often in a set of data. In our list the value that appears most often is n. Therefore n is the mode of the numbers in the list.

Only statement (2) is useful in finding the value of n as it states that the mode of the numbers in the list is 16.

Example Question #3312 : Gmat Quantitative Reasoning

What is the value of  in the list of numbers above?

(1) .

(2) The mode of the numbers in the list is .

Possible Answers:

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Each Statement ALONE is sufficient.

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

Statements (1) and (2) TOGETHER are not sufficient.

Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient.

Correct answer:

Each Statement ALONE is sufficient.

Explanation:

The mode is the value that appears most often in a set of numbers. In the list given, the value that appears the most is m. Therefore, m is the mode in the list of numbers given.

(1)

Therefore, .

 Statement (1) is sufficient

 

(2) The mode of the numbers in the list is 6.

Therefore, .

Statement (2) is sufficient

Each Statement ALONE is SUFFICIENT

 

Example Question #3313 : Gmat Quantitative Reasoning

What is the sum of  and ?

(1) The mode of the numbers in the list is .

(2) The product of  and  is .

Possible Answers:

Statements (1) and (2) TOGETHER are not sufficient.

Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient.

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Each Statement ALONE is sufficient.

Correct answer:

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Explanation:

The mode is the value that appears most often in a set of data. In our list the value that appears most often is 2y. Therefore 2y is the mode of the numbers in the list.

(1) The mode of the numbers in the list is 20.

 

  

We still don't know the value of x. Statement (1) ALONE is not sufficient.

(2) The product of x and y is 150.

 

Statement (2) ALONE is not sufficient.

Using both statements, we can write

 

 

Therefore,

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

 

Example Question #1201 : Data Sufficiency Questions

Find the mode of the following set of numbers:

Possible Answers:

Correct answer:

Explanation:

The mode is the number that occurs most frequently. Therefore, our answer is .

Example Question #1201 : Data Sufficiency Questions

What is the value of  in the list of numbers above?

(1) The mode of the numbers in the list is .

(2) .

Possible Answers:

Statement (2) ALONE is sufficient, but Statement (1) ALONE is not sufficient.

Each Statement ALONE is sufficient.

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

Statements (1) and (2) TOGETHER are not sufficient.

Both statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Correct answer:

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

Explanation:

The mode is the value that appears most often in a set of data. In our list the value that appears most often is m+1. Therefore m+1 is the mode of the numbers in the list.

Only statement (1) is useful in finding the value of m as it states that the mode of the numbers in the list is 14.

Statement (1) ALONE is sufficient, but Statement (2) ALONE is not sufficient.

 

Example Question #1201 : Data Sufficiency Questions

What is the median number of students assigned per workshop at School R?

(1) 30% of the workshops at School R have 6 or more students assigned to each workshop.

(2) 40% of the workshops at School R have 4 or fewer students assigned to each workshop.

Possible Answers:

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

D. EACH statement ALONE is sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

Correct answer:

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

Explanation:

Looking at statements (1) and (2) separately, we cannot get the median number since we don’t know the 50th percentile. However, putting the two statements together, we know that the 50th percentile is 5. So the median is 5.

Example Question #1202 : Data Sufficiency Questions

The median of the numbers , , , and  is . What is  equal to?

Possible Answers:

None of the other answers are correct.

Correct answer:

Explanation:

The four numbers  appear in ascending order, so their median  must be the arithmetic mean of the middle two numbers. Therefore, 

 

Example Question #1203 : Data Sufficiency Questions

What is the mean of this set?

1) 

2) 

Possible Answers:
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.
BOTH statements TOGETHER are 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.
Statement 1 ALONE is sufficient to answer the question, but Statement 2 ALONE is not sufficient to answer the question.
Correct answer: EITHER statement ALONE is sufficient to answer the question.
Explanation:

If , then .

 

If , then

 

The two statements are equivalent. This is enough to allow the mean to be found:

The answer is that either statement alone is sufficient to answer the question.

Example Question #1204 : Data Sufficiency Questions

Data Sufficiency Question

The mean of 8 numbers is 17. Is the median also 17?

1. The range of the numbers is 11.

2. The mode is 17.

Possible Answers:

both statements taken together are sufficient to answer the question, but neither statement alone is sufficient

statements 1 and 2 together are not sufficient, and additional data is needed to answer the question

statement 2 alone is sufficient, but statement 1 alone is not sufficient to answer the question

statement 1 alone is sufficient, but statement 2 alone is not sufficient to answer the question

each statement alone is sufficient

Correct answer:

statements 1 and 2 together are not sufficient, and additional data is needed to answer the question

Explanation:

The range tells us the difference between the maximum and the minimum values, but provides no information about the median. The mode indicates the number that appears most frequently in the data set. While it is possible that the median is 17, it is impossible to determine the median from the data provided.

Example Question #1 : Dsq: Calculating Median

On Monday, 40 people are asked to rate the quality of product A on a seven point scale (1=very poor, 2=poor.....6=very good, 7=excellent).  

On Tuesday, a different group of 40 is asked to rate the quality of product B using the same seven point scale. 

The results for product A:

7 votes for category 1 (very poor);

8 votes for category 2;

10 votes for 3;

6 vote for 4;

4 votes for 5;

3 votes for 6;

2 votes for 7;

The results for product B:

2 votes for category 1 (very poor);

3 votes for category 2;

4 votes for 3;

6 vote for 4;

10 votes for 5;

8 votes for 6;

7 votes for 7;

It appears that B is the superior product.

Which one of the following statements is true?

Possible Answers:

The median score for product A is less than the mean score for product A.

The median score of product A is greater than the median score of product B.

The median score of product A is greater than the mean score of product A.

The median score of product B is less than the mean score of product B.

The mean score of product A is greater than the mean score of product B.

Correct answer:

The median score for product A is less than the mean score for product A.

Explanation:

Median of A = 3

Mean of A = 3.2

Median of B = 5

Mean of B = 4.8

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