For the following four questions determine which sampling technique was used from the list below.

stratified

cluster

convenience

systematic

random

1. Thirty-five sophomores, 69 juniors and 24 seniors are randomly selected from 461 sophomores, 328 juniors and 558 seniors at a certain high school. What sampling technique is used.
2. Every tenth widget on an assembly line is checked for defects.
3. At a local community college, five statistics classes are randomly selected and all of the students from each class are interviewed.
4. A community college student interviews everyone in a statistics class to determine the number of hours of sleep they get every night.