Question

The president of a company wants to know about how many of the office chairs in the building need to be replaced. Which sampling method will result in a sample that is not biased?

She puts notices in the break rooms asking employees to e-mail her about the condition of their chairs.

She asks every other employee she sees in the cafeteria about his chair.

She gives a list of employee names to the maintenance supervisor and tells him to inspect the chair of every fifth employee.

She inspects every chair in the sales department.