150, 200, 250, n
Which of the following could be the median of the 4 integers listed above?
I. 175
II. 215
III. 235
A. I only
B. II only
C. I and II only
D. II and III only
E. I, II, and III
In cases where there is an EVEN number of values (as there are in this question), the median will be the average of the two middlemost values when all values are arranged in ascending order.
We can already see that
200 will be one of the two middlemost values, so let's check the various options for median and see what the
other number needs to be to get each target median.
I. 175
If the median is 175, then it must be the case that (
200 +
other number)/2 = 175
So, in this case, the
other number must be
150.
This is entirely possible, if n
< 150. For example if n = 100, then the values would be {100,
150, 200, 250}, in which case the median is 175.
So, option I is possible.
II. 215
If the median is 215, then it must be the case that (
200 +
other number)/2 = 215
So, in this case, the
other number must be
230.
This is entirely possible, if n = 230. The values would be {150, 200,
230, 250}, in which case the median is 215.
So, option II is possible.
III. 235
If the median is 235, then it must be the case that (
200 +
other number)/2 = 235
So, in this case, the
other number must be
270.
Here, we have a PROBLEM. If the other number is
270, then the values are {150, 200, 250,
270}, in which case 200 and 270 are NOT the two middlemost values. The two middlemost values are 200 and 250, giving us a median of 225 (not 235).
So, option III is NOT possible.
Answer:
C
Cheers,
Brent