Determine if the following situations use random or nonrandom sampling. Then, identify what type of random or nonrandom sampling technique is used. Respondents are chosen from a list in the telephone...

Determine if the following situations use random or nonrandom sampling. Then, identify what type of random or nonrandom sampling technique is used.

1. 
   Respondents are chosen from a list in the telephone directory.
   


2. 
   There are 30 freshmen, 20 sophomores, 10 juniors, and 5 seniors enrolled in a certain course. Samples are to be taken from them according to the total number of students per year level.
   


3. 
   Minority groups of senators are to be interviewed.
   


4. 
   Every five files out of 500 files will be chosen.
   


5. 
   Animals going astray are to be observed.
   


6. 
   Two thousand respondents nationwide, from regions down to barangays, are selected for a national election survey.
   


7. 
   Five hundred “likes” in Facebook are used as a basis for making a decision.
   


8. 
   Selected respondents for a study are those with Acquired Immune Deficiency Syndrome (AIDS).
   


9. 
   Ten names of students were picked out from a box containing 1,000 names written in rolled papers.
   
   


10. 
    Selected vehicles are classified according to the last number of their plates as odd or even.