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First find the median of 46,64,87,41,58,77,35,90,55,92, and 33. If 92 is replaced with 99 and 41 is replaced with 43 in the data, then find the new median. What is the difference between the old median and the new median?
2
3
6
0
0
Sort the data to identify the middle term. Since there are n=11 values, the median is the 6th value in the ordered sequence.
Data set: {46, 64, 87, 41, 58, 77, 35, 90, 55, 92, 33}. Replacements: 92 is replaced by 99, and 41 is replaced by 43.
Median=middle┬аvalue┬аin┬аan┬аordered┬аset
Sort the data to identify the middle term. Since there are n=11 values, the median is the 6th value in the ordered sequence.
Failing to re-sort the data after performing the replacements, which changes the positions of elements in the ordered list.
Sort the original data
List the original data points in ascending order to find the median: {33, 35, 41, 46, 55, 58, 64, 77, 87, 90, 92}.
33,35,41,46,55,58,64,77,87,90,92
Find the old median
With n=11 terms, the median is the 6th term. The 6th term is 58.
MedianoldтАЛ=58
Modify the data set
Replace 92 with 99 and 41 with 43. New data: {46, 64, 87, 43, 58, 77, 35, 90, 55, 99, 33}.
Newset={33,35,43,46,55,58,64,77,87,90,99}
Find the new median
Sorting the new data: {33, 35, 43, 46, 55, 58, 64, 77, 87, 90, 99}. The 6th term remains 58.
MediannewтАЛ=58
Calculate the difference
Difference = тИгMedianoldтАЛтИТMediannewтАЛтИг=тИг58тИТ58тИг=0.
Difference=0
D is correct because both the old median and the new median are 58, resulting in a difference of 0.
This concept relates to the 'Robustness of Statistics'; note that the median is less sensitive to extreme outliers than the mean.