GATE CS 2024 Set 1 Q.3: Quantitative Aptitude

Consider the following sample of numbers:

9, 18, 11, 14, 15, 17, 10, 69, 11, 13

The median of the sample is

13.5

18.7

Official answer and solution

Solution

Sort the 10 sample numbers in ascending order and take the average of the 5th and 6th elements.

Sorting the $n = 10$ numbers in non-decreasing order gives:

9,\; 10,\; 11,\; 11,\; 13,\; 14,\; 15,\; 17,\; 18,\; 69

Since $n = 10$ is even, the median is the average of the $\frac{n}{2} = 5\text{th}$ and $\left(\frac{n}{2} + 1\right) = 6\text{th}$ values:

\text{Median} = \frac{13 + 14}{2} = 13.5

Final answer

Option (A)

Common trap

Computing the mean (18.7) or mode (11) instead of sorting the array first to find the median.

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