CA Foundation · Quantitative Aptitude · Measures of Central Tendency and Dispersion
The following 11 observations are already arranged in ascending order: 12, 15, 18, 22, 25, 28, 30, 35, 40, 45, 50. Using the position formula for ungrouped data, what is the third quartile (Q3)?
The third quartile is 40. With 11 ordered observations, Q3 lies at position 3(n+1)/4 = 9, and the ninth value in the list is 40. Choosing 35 would mean using the eighth item, which is the wrong position.
- A35
- B40Correct
- C45
- D38
Explanation
For n = 11, Q3 is the item at position 3(n+1)/4 = 3×12/4 = 9. The 9th value in the ordered list is 40. The value 35 is the 8th item, so it would result from a position that is one place too low.
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