To solve this problem, we need to understand the concept of the median for a set of four numbers
a, b, c, and d.
When the numbers are ordered in ascending order as a≤b≤c≤d, the median is defined as the average of the two middle numbers. Therefore, the median of the four numbers is given by:
Median = b+c/2
Option I:
[a+d][/2]
This expression is the average of the smallest and the largest numbers. It can only be the median if
b=a and c=d, meaning that the middle two numbers are equal to the smallest and largest numbers. While this situation is possible, it is quite specific. Therefore, this option can be the median in certain cases.
Option II:
[a+b+c ]/[/3]
This expression represents the average of the first three numbers. For this to be the median,
b+c must be equal to 2× [a+b+c[/3] which is not generally possible, but under certain conditions where a=b=c, this could be equal to
b or c. Therefore, this option can also be the median under specific conditions.
Option III:
a+b+c
This expression is a sum of the first three numbers. There is no scenario where the sum of three numbers could represent the median of four numbers. Therefore, this option cannot be the median.
Option IV:
a+b+c+d
This expression is the sum of all four numbers. There is no scenario where the sum of all four numbers could represent the median of four numbers. Therefore, this option cannot be the median.
Answer: C. I and II only