A principal wants to determine the average time students spend on homework. She surveys only the students found in the school library after school. Why is this sample likely not representative?

It overrepresents students who prefer to do their homework at school.

It includes students from all grade levels.

The sample was collected after school hours.

The principal conducted the survey herself.

A city council wants to know if residents support a new public swimming pool. Which of the following survey methods would produce the most representative sample?

Surveying all members of the local swim team.

Asking for opinions from families at a public park on a Saturday.

Calling a random selection of phone numbers from the city's residential directory.

Polling shoppers at the city's largest mall.