Shortcut Trick
Arrange the given data in ascending order:
18, 28, 33, 49, 52, 54, 55, 56, 60, 61, 80
Total number of observations (n) = 11 (which is an odd number).
Median = ((n + 1) ÷ 2)th term = (12 ÷ 2)th term = 6th term = 54
∴ The correct answer is 54.
Alternate Method
Given:
The dataset is: 61, 55, 18, 49, 52, 80, 60, 33, 54, 56, 28
Formula Used:
To find the median of a dataset:
- Arrange the data in ascending or descending order.
- If the number of observations (n) is odd:
Median = ((n + 1) ÷ 2)th observation
- If the number of observations (n) is even:
Median = [ (n ÷ 2)th observation + ((n ÷ 2) + 1)th observation ] ÷ 2
Calculations:
Arrange the given observations in ascending order:
⇒ 18, 28, 33, 49, 52, 54, 55, 56, 60, 61, 80
Count the total number of observations (n):
⇒ n = 11
Since n is odd, we use the odd formula for median:
⇒ Median = ((11 + 1) ÷ 2)th term
⇒ Median = (12 ÷ 2)th term
⇒ Median = 6th term
Looking at the arranged data, the 6th term is 54.
⇒ Median = 54
Explanation of incorrect options:
⇒ Option (1) 55 is the 7th term, which is incorrect because it is not the exact middle term of the sorted dataset.
⇒ Option (2) 53.5 is incorrect as it is the average of 52 and 55, which does not represent the middle term of this odd-numbered dataset.
⇒ Option (4) 54.5 is the average of 54 and 55, which would only be calculated if the number of terms (n) was even.
∴ The correct answer is 54.
Additional Information
Median for Even Number of Terms
When the number of observations (n) is even, the median is the average of the (n ÷ 2)th and ((n ÷ 2) + 1)th terms.
Mean, Median, and Mode Relationship
For a moderately skewed distribution, the empirical relationship is: Mode = 3 × Median − 2 × Mean.
Effect of Outliers
Unlike the mean, the median is a robust measure of central tendency and is not affected by extreme values (outliers) in the dataset.