A manufacturing company with 300 employees. There are 6 departments in the company, with a coffee machine per department. Its own cafeteria.

The company manager has heard that employees are complaining that the coffee machines keep breaking down. The company manager would like to know the worker's opinion on the existing coffee machines. The manager and decides to conduct a survey by placing a survey box next to each coffee machine. The survey box has a sign asking employees to submit a survey form with answers on a few questions about the coffee machines After several weeks, there are 180 filled in responses in the survey box.

a) State the value of the population size.

b) State the value of the sample size.

c) Describe the sampling frame used by the company manager.

d) Describe one type of bias this sample may suffer from. Briefly explain your reasoning.

e) If you could advise the company manager about a better sampling method, what would you tell them to do? Explain.