The median of a set of 9 distinct observations is 20.5. If each of the largest 4 observations of the set is increased by 2, then the median of the new set:
Answer: D
The median of 9 observations is the 5th term when arranged in order. Its value is 20.5.
The change is made to the largest 4 observations, which are the 6th, 7th, 8th, and 9th terms.
Since these changes do not affect the value or position of the 5th term, the median of the new set will remain the same.