Which expression has the same sum as the one below?
-15+6
Su
15+6
-6+(-15)
15+(-6)
6+(-15)

Identify all the cases where non-probability sampling is used when attempting to study the characteristics of a large city. studies on every subject in the population divide a population in groups and obtain a sample studies with a limited amount of time demonstrate existing traits in a population studies with the nth person selected