GMAT Math : Descriptive Statistics
Study concepts, example questions & explanations for GMAT Math
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Example Questions
Example Question #2 : Arithmetic Mean
The average of 10, 25, and 70 is 10 more than the average of 15, 30, and x. What is the missing number?
The average of 10, 25, and 70 is 35:
So the average of 15, 30, and the unknown number is 25 or, 10 less than the average of 10, 25, and 70 (= 35)
so
Example Question #3 : Arithmetic Mean
What is the average of 2x, 3x + 2, and 7x +4?
not enough information
7x
4x + 2
4
3x + 4
4x + 2
Example Question #3 : Arithmetic Mean
The average high temperature for the week is 85. The first six days of the week have high temperatures of 89, 76, 92, 90, 80, and 84, respectively. What is the high temperature on the seventh day of the week?
Example Question #4 : Arithmetic Mean
Jimmy's grade in his finance class is based on six equally-weighted tests. If Jimmy scored 98, 64, 82, 90, 70, and 88 on the six tests, what was his grade in the class?
Example Question #2031 : Problem Solving Questions
Sandra's grade in economics depends on seven tests - five hourly tests, a midterm, and a final exam. The midterm counts twice as much as an hourly test; the final, three times as much.
Sandra's grades on the five hourly tests are 84, 86, 76, 89, and 93; her grade on the midterm was 72. What score out of 100 must she achieve on the final exam so that her average score at the end of the term is at least 80?
She cannot achieve this average this term
This is a weighted mean, with the hourly tests assigned a weight of 1, the midterm assigned a weight of 2, and the final assigned a weight of 3. The total of the weights will be
If we let 
For Sandra to get a final average of 80, then we set the above equal to 80 and calculate 
Example Question #21 : Descriptive Statistics
Consider the following set of numbers:
85, 87, 87, 82, 89
What is the mean?
Example Question #22 : Descriptive Statistics
Consider the following set of numbers:
85, 87, 87, 82, 89
What is the median?
Reorder the values in numerical order:82, 85, 87, 87, 89
The median is the center number, 87.
Example Question #11 : Calculating Arithmetic Mean
Find the mean of the sample data set.
The mean of a sample data set is the sum of all of the values divided by the total number of values. In this case:
Example Question #12 : Calculating Arithmetic Mean
The average of the following 6 digits is 75. What is a possible value of 
80, 78, 78, 70, 71,
Therefore, the sum of all 6 digits must equal 450.
Subtract 377 from both sides.
Example Question #25 : Descriptive Statistics
When assigning a score for the term, a professor takes the mean of all of a student's test scores except for his or her lowest score.
On the first five exams, Donna has achieved the following scores: 76, 84, 80, 65, 91. There is one more exam in the course. Assuming that 100 is the maximum possible score, what is the range of possible final averages she can achieve (nearest tenth, if applicable)?
Minimum 66; maximum 71.8
Minimum 66; maximum 99.2
Minimum 79.2; maximum 86.2
Minimum 79.2; maximum 99.2
Minimum 80, maximum 84
Minimum 79.2; maximum 86.2
The worst-case scenario is that she will score 65 or less, in which case her score will be the mean of the scores she has already achieved.
The best-case scenario is that she will score 100, in which case the 65 will be dropped and her score will be the mean of the other five scores.
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