There are 396 marbles in a bag. The bag contains red, yellow, and purple marbles. If the ratio of red to yellow
marbles is 2:3 and the ratio of yellow to purple marbles is 1:2, how many yellow marbles are in the bag?

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