Question

maria wonders what pets the students at her school prefer. so, she plans to ask a small sample of them. pick all the ways of sampling the students that would produce a representative sample. maria assigns a number to each student. she uses a computer to randomly pick 20 of them to ask. maria randomly chooses a dog park. she asks 20 students she sees there. at marias school, every student is in a science class. maria asks 2 students chosen randomly from each of the 10 science classes.

Explanation:

A representative sample should reflect the entire population. Assigning numbers to all students and randomly picking (simple random sampling) and randomly choosing students from each science - class (stratified sampling) are valid methods as they cover the whole student population at the school. Asking students at a dog - park is a biased sample since students at a dog - park are more likely to like dogs, not representing all students at the school.

Answer:

A. Maria assigns a number to each student. She uses a computer to randomly pick 20 of them to ask.
C. At Maria's school, every student is in a science class. Maria asks 2 students chosen randomly from each of the 10 science classes.