Teachers Work Experience Statistics
XAT 2024 · Quantitative Ability & Data Interpretation · Hard · Statistics
Passage / data set
The upper hinge of a dataset is the median of all the values to the right of the median of the dataset in an ascending arrangement, while the lower hinge of the dataset is the median of all the values to the left of the median of the dataset in the same arrangement.
For example, consider the dataset 4, 3, 2, 6, 4, 2, 7. When arranged in ascending order, it becomes 2, 2, 3, 4, 4, 6, 7. The median is 4 (the bold value), and hence the upper hinge is the median of 4, 6, 7, i.e., 6. Similarly, the lower hinge is 2.
A student has surveyed thirteen of her teachers, and recorded their work experience (in integer years). Two of the values recorded by the student got smudged, and she cannot recall those values. All she remembers is that those two values were unequal, so let us write them as and , where . The remaining eleven values, as recorded, are: 5, 6, 7, 8, 12, 16, 19, 21, 21, 27, 29. Moreover, the student also remembers the following summary measures, calculated based on all the thirteen values:
- Minimum: 2
- Lower Hinge: 6.5
- Median: 12
- Upper Hinge: 21
- Maximum: 29
Question 1 of 3
Which of the following is a possible value of ?
- A.
2
- B.
6
- C.
8
- D.
13
- E.
29
C
Explanation
Since the minimum value is 2 and 2 is not among the 11 known values, the smaller smudged value must be 2. With , we have 12 values: 2, 5, 6, 7, 8, 12, 16, 19, 21, 21, 27, 29 plus . The median of 13 values is the value in sorted order, which is given as 12. For 12 to be the element, must be . The lower hinge is the median of the first 6 values. The first 6 values are 2, 5, 6, 7, 8, and . For their median to be 6.5, must be greater than 7 (so the middle two values are 6 and , giving , or can be 8, 9, 10, 11, 12 giving lower hinge between 6.5 and 7). Among the options, 8 lies in the valid range .
Question 2 of 3
Based on the information recorded, which of the following can be the average work experience of the thirteen teachers?
- A.
12
- B.
12.5
- C.
13
- D.
13.5
- E.
14
E
Explanation
Sum of 11 known values . Adding , sum of 12 values . can range from 7 to 12. If , the total sum . Average .
Question 3 of 3
While rechecking her original notes to re-enter the smudged values of and in the records, the student found that one of the eleven recorded work experience values that did not get smudged was recorded wrongly as half of its correct value. After re-entering the values of and , and correcting the wrongly recorded value, she recalculated all the summary measures. The recalculated average value was 15. What is the value of ?
- A.
7
- B.
9
- C.
10
- D.
12
- E.
Cannot be determined from the given information.
C
Explanation
Recalculated average Recalculated total sum . The sum before correction was . Correcting a value that was recorded as half means adding its original value to the sum. . and . Testing pairs where :
- If , , which is a valid value from the list. Thus .
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