List I: 15, 12, 17, 20 List II: x,15, 12, 17, 20	Choose the correct choice from the following answers.
A) 15
B) 16
C) 20
D) 22
E) 24
List I has even number of terms, thus its median is the average of two middle terms (when arranged in ascending/descending order), so median=(15+17)/2= 
<gadget id="calculator">(15+17)/2</gadget>
<output>16</output>
16   List II has odd number of terms, thus its median is the middle term (when arranged in ascending/descending order). As no other number in the list equal to 16, then x=16.   Answer: 16
<result>B</result>
List I: 15, 12, 17, 20 List II: x,15, 12, 17, 20