Question

sharon 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. sharon assigns a number to each student. she uses a computer to randomly pick 20 of them to ask. sharon randomly chooses a dog park. she asks 20 students she sees there. at sharons school, every student is in a science class. sharon asks 2 students chosen randomly from each of the 10 science classes.

Explanation:

Step1: Analyze the first sampling method

Sharon assigns a number to each student and uses a computer to randomly pick 20 of them. This is a simple random - sampling method. In simple random sampling, every student has an equal chance of being selected, so it is likely to produce a representative sample.

Step2: Analyze the second sampling method

Sharon randomly chooses a dog park and asks 20 students she sees there. Students at a dog park are more likely to be dog - lovers. This sample is biased (not representative) because it over - represents students who like dogs (since they are at a dog park) and under - represents students who may prefer other pets or no pets at all.

Step3: Analyze the third sampling method

At Sharon's school, every student is in a science class. Sharon asks 2 students chosen randomly from each of the 10 science classes. This is a stratified sampling method (stratified by science classes). Since the sample is drawn proportionally (2 students from each of the 10 classes) from the entire population (all students in the school, as all students are in science classes), it is likely to produce a representative sample.

Answer:

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